Stanley is a man without a past. The only signficant things that are known about his past are that he was an officer in the army and he is a Polish immigrant. The reason that a photograph of Stanley in his uniform is displayed in their home is because both Stanley and Stella take pride in his 'macho - male' image. Nothing else is known about his past; and hence Stanley is a man who lives very much in the present, contending with present-day reality. He is a self-made man, virile and symbolic of the new America, which is classless and made of up of new immigrants. As such, he has no time for Blanche who lives more in the past than in the present.
Blanche, on the other hand, lives more in the past than in the present. She came from a world of gracious living; from a palatial home with "white columns" in a plantation run with slave labour. Women, from the land-owning class, did not need to work in order to live. Instead they merely had to be young and pretty in order to get hold of an eligible husband who would look after them for the rest of their lives. Unfortunately for Blanche who had been brought up in this world, things were changing rapidly in the society around her. Plantations were disintegrating in the aftermath of the civil war and plantation owners were becoming impoverished. Post world war 11, and the changes that it brought put the final seal on the coffin of plantation living. While Stella adapts to these changes, by leaving the dying plantation and getting herself a job as well as by marrying one of the new breed of Americans on the rise, Blanche clings on to her memories of a romanticized past. Thus she tries to portray herself as young, desirable and virginal in hopes of finding a husband who will be both provider and protector. She tries to re-create the chivalric code of behaviour that governed relations between men and women in the old South, in the modern New Orleans. Thus she makes Mitch present her with a bunch of flowers on their first date, which she accepts calling him "My Rosenkavalier".
Thus she still clings to the belief that she is the virginal (though she had had many relationships in the past); young belle that she had been in the past and behaves as she were still this. Stanley, who is untroubled by any memories of the past, finds her grotesque and has little sympathy for her illusions.