play: Tom's version of events as he speaks them or the events that occur as the other characters act them out?

Stylistically, Tom's speech as narrator differs from his speech as character. His "narrator" voice is loftier, more erudite, prone to longer sentences with rhythm and a feeling of poetry in them. The content of his speech allows for him to convey important expository information to the audience, mainly in giving context to the events of the play itself, and their place within the past, the present, or the future. But he is also able to comment upon the play's events and themes in a sort of philosophical way—acting as a sort of dramaturge or even critic. It is a most provocative structure that Williams gave to this play, and that is one of the reasons The Glass Menagerie is such an iconic work of American theatre.

Tom is the narrator of the play, and its protagonist; he tells the audience early on that it is a memory play, thus informing the audience that the memories he shares will be from his own perspective. Stylistically, this means that Tom could be considered at least a biased, if not a somewhat unreliable, narrator. His deep unhappiness over the responsibilities that have been foisted upon him cause him to vilify his mother and create pity for himself and his sister, but audiences are savvy enough to understand that there are no heroes, villains, or clear-cut judgments in what emerges as a tragically dysfunctional family dynamic.

It is fair to say that Tom wants us to believe that Amanda and Laura suffer delusions and that he sees himself as an artist who must suffer for his art: he escapes to pursue his writing career but is doomed to carry enormous guilt for abandoning his single mother and disabled sister.

Audiences also are meant to understand that Tom's "writerly" touches inform the play. The perfect symbolism of the glass menagerie, the archetype of the faded Southern belle, and the grandiosity of the drama in such a precise setting are more reflective of Tom's artistic imagination than any realism.

It has been said that this play, one of Tennessee William's best-loved works, is somewhat autobiographical. The character of Laura is based upon Williams' sister, Rose. By making Tom into a character and a narrator, so the narrator comments upon the world of the characters, Williams is able to reveal elements of his own process as a writer (being outside the world of his characters but also inhabiting those to whom he feels closest).

If Tom had been only a character, or only a narrator, the autobiographical association might have been even stronger, drawing emphasis away from the story, which is moving on many levels and which has elements of drama, comedy, and romance. By having Tom embody a character in the play who also comments upon his own life, as well as his relationship to the other characters, the autobiographical presence of the author becomes more subtle and diffused, because Tom interacts with the world of the play on at least two different levels.

There is also a sort of revelatory tone at work, allowing audiences to understand that Williams experienced his own life as someone who would one day write about it, and that self-awareness comes through in Tom's narrator speeches. There's also a suggestion that Williams may well have felt similarly about all of his characters and work, but allowed The Glass Menagerie to be the most significant and recognizably personal of his plays.

Tom's role as both narrator and character is an interesting one.  Tom is the most appropriate to tell the story of his family because he is the one who is finally able to break free from the rut that he was in.  Laura and Amanda have not broken free and probably won't, in my opinion. Tom can tell the story with a clearer picture of what living with Amanda and Laura was like because he seems to be the only character who is a tad more rooted in reality and is finally willing to leave the oppressiveness of his home with his mother and sister and find out what it is like to be alone.  

I'm not sure exactly what you would like to know about his dual role, but you can find some information on this website's study guide at the following link :

http://www.enotes.com/glass-menagerie/characters

It discusses his dual role towards the bottom of the paragraph, explaining how he is retelling the events that transpired that night before he left the house for good. However, though he has achieved physical detachment, emotionally speaking this evening and its events still linger in his mind. 

Tom's mode of speech does display slight differences, depending upon whether he is playing himself in the action, or playing himself as a narrator. As narrator, he has a kind of omniscience, in that he knows what has already happened into the future. Physically, his placement on the stage can indicate his status. For example, in the first act, he stands apart from a scene with Amanda while she continues speaking to his chair as if he is seated there in the room.

Tom's words are more sophisticated and his sentence structure is more elaborate when he is the narrator. When speaking to his mother, he is often frustrated and angry, and speaks in short bursts:

After the fiasco at Rubicam's Business College, the idea of getting a gentleman caller for Laura began to play a more and more important part in Mother's calculations. It became an obsession. Like some archetype of the universal unconscious, the image of the gentleman caller haunted our small apartment.

Throughout the play, Tom also speaks of dreams and fantasies with the same sort of dreamy distraction his mother does. Tom, however, knows these dreams never amounted to anything and acknowledges his own shortcomings. When he says "And so, goodnight" at the end of the play, it's a way of closing the book on those dreams, but also understanding that Laura's daily existence was a peaceful one. She would wake up the next day and be as content as she had been before, once she let go of her mother's unrealistic expectations. Tom could not continue to live with his family; like his father, he sought escape. The images of night and day in the play reiterate this idea of daily life's reality versus the long-range hopes and dreams of a lifetime.

When Tom addresses the audience, his speech is much more erudite and lofty than when he simply talks to Amanda, Laura, and Jim in the play. His age difference and his experience gleaned throughout the years easily account for this discrepancy. Although the exact time lapse is unknown, Tom is definitely a more mature man than he is in his role as a breadwinner living with his mother and sister against his will.

Form is also determined by function. Whereas the speech throughout the play is natural, spontaneous dialogue, Tom's language to the audience is more like 'a speech' or public address. The form Tom chooses is a deliberate one; he takes a certain poetic license when narrating the story. (The true "Shakespeare" in Tom finally comes out!) In the opening lines, he explains that unlike a magician, he is representing fact as a kind of fantasy, modulated and toned even as memory is never really an exact "replica" of the true event it represents.

As a narrator, Tom is looking back in time, retrospectively. As such, he has had the time to analyze the events of the night when he left the household, and he has been away from his family long enough to look back objectively at the dynamics that were taking place in the Wingfield household.

The tone that he uses as a narrator is, therefore, much more mature, calm, and organized in comparison to the language that he uses "in the moment" as a character.

Clearly, the "Tom" that still lives with Amanda and Laura is a very confused, and a much less mature, man. He is on the brink of making a life-changing event, and he carries with him all the anxiety, angst, frustration, and denial that come with having to make a big decision.

The Tom that still lives in the apartment is someone who is so fed up with life, and so insecure about the changes that he has to make, that he lashes out against the things that he sees as obstacles.

What do you think I’m at? Aren’t I supposed to have any patience to reach the end of, Mother? [[...] It seems unimportant to you, what I’m doing – what I want to do – having a little difference between them!

Look! I’d rather somebody packed up a crowbar and battered out my brains—than go back mornings! I go! Every time you come in yelling that Goddamn ‘Rise and Shine! Rise and Shine!’ I say to myself, ‘How lucky dead people are!’ But I get up.

This happens particularly with Amanda, his mother. Being that she is a possessive woman, unable to move on from the past, and unwilling to make personal changes in view of the changing times, Tom sees her as his principal nemesis. He is trying to become Amanda's literal opposite by trying to move on, trying to change, and trying to adapt to life. The more time he spends near her, the more difficult this becomes. 

Once he is out of the house, however,  time passes, and his emotions neutralize a little bit more compared to when he was at the household. Tom is even willing to find a degree of understanding for his mother and sister, and now sees them as victims of circumstances, and of their own, co-dependent inability to break free and move on from the shadow of the father. 

Therefore, his language is more forgiving, sentimental, nostalgic, composed and even poetic and figurative.

Man is by instinct a lover, a hunter, a fighter, and none of those instincts are given much play at the warehouse.

I didn’t go to the moon – I went much further—for time is the longest distance between two poles. Not long after that I was fired for writing a poem on the lid of a shoe-box. 

Still, the one thing that he hurts for the most is the fact that he could not help his sister become liberated and free. He had to leave her behind in order to save himself. For that reason, his speech will always carry a gravitas that denotes guilt and the wish to be able to help her in some way.

Tom gives up his own opportunities for advancement and adventure in order to support his family.  His tragic flaw is that he cannot fully accept the responsibility to act as the father, nor is he fully willing to walk away from the family to pursue his own goals.  He gets in trouble at work because he is distracted, but he isn't willing to walk away from the family and chase his own dreams until after he brings Jim home, and even then his description of events years after the story occurs demonstrate his inability to ever fully escape from the difficulties he faced at the time of the story's action.

Tom is arguably a heroic figure, though a flawed and tragic one. He is free-spirited and creative despite the squalid conditions in which he finds himself. The opposition of his mother, chained to her Southern belle past, also grinds him down with her nagging and attempts to control him. For a long time, he does nothing about his yearnings for adventure and beauty save drink heavily and attend the movies every night. By the end of the story, he leaves his unsatisfying life, which takes real courage to do since his mother, Amanda, tries to guilt him into staying where he's always been, a state which could potentially lead to the death of his creative potential.

It could be argued that Tom's final actions are selfish, since they involve leaving his sister, but the situation is far more complex. Amanda is a well-meaning but stifling figure, trapping both her children in an eternal childhood of sorts. One scene in which she insists on fixing a cowlick in Tom's hair, as though he were a little boy, demonstrates this in a casual way. Tom's final lines in the play suggest a pained but wiser man now able to make his own way in life, even if his life has not become any easier.