The glass menagerie is symbolic of the fantasy world or illusion that Laura creates to protect her from reality. She would rather live in the world of glass figures, especially the world of the unicorn, her favorite animal, a creature of fairy tales, than in the world she inhabits. Combine this with the music that Laura plays on the Victrola and she escapes into a dream world, a place she would happily remain if her mother would allow it.
Reality for Laura is defined by her failed attempt at the Rubicam Business College. In the real world, Laura has a great deal of difficulty dealing with people and stress, demanding situations, she escapes the confines of the business school's environment by visiting museums and zoos, places that Laura feels more at ease, not threatened.
Amanda's stories of her days in Blue Mountain when she received 17 gentleman callers in one day represent illusion, this too protects Amanda from the harshness of reality which is defined by her life as an abandoned wife.
Amanda switches from illusion to reality constantly, visiting her memories just enough to cheer herself up so that she can look her real life square in the eyes. Her reality is rather gloomy, dominated by disappointment, both in herself and in her children, which she believes to be her fault. Her daughter does not want a life outside the apartment, has no interest in getting a job or finding a husband. Tom, who is becoming like his angry, detached father more and more every day scares Amanda.
Tom's reality is the apartment, the demands that his mother makes on him, the need to care for his sister and the ugliness of the shoe warehouse where he works. To escape this reality, he writes poetry and reads. He also escapes into the movies, the ultimate illusion, finding adventure for a few hours each night sitting in his seat at the local theater.
The magician who performs at the movie theater presents another symbol of illusion, the coffin that is nailed shut from which he escapes. Tom feels like he is nailed shut in a coffin, the apartment, and he can't escape.
The lights going out at the end of the play are also symbolic of illusion vs. reality. In the early part of the visit from Jim, the gentleman caller, the lights are on, Jim, who himself is a representative of reality, accepts the lights going out with ease. The lights going out, because of Tom's negligence to pay the light bill, is symbolic of illusion being replaced by reality, that which is represented by the darkness that embraces the family. Particularly Amanda and Laura who are left in the dark by Tom, who escapes the apartment never to return.