Reality and Illusion
Death of a Salesman uses flashbacks to present Willy's memory during the reality. The illusion not only “suggests the past, but also presents the lost pastoral life.” Willy has dreamed of success his whole life and makes up lies about his and Biff's success. The more he indulges in the illusion, the harder it is for him to face reality. Biff is the only one who realizes that the whole family lived in the lies and tries to face the truth.
Willy Loman dreams of being a successful salesman like Dave Singleman, somebody who has both wealth and freedom. Willy believes that the key to success is being well-liked, and his frequent flashbacks show that he measures happiness in terms of wealth and popularity. One analyst of the play writes: “Society tries to teach that, if people are rich and well-liked, they will be happy. Because of this, Willy thought that money would make him happy. He never bothered to try to be happy with what he had …” Willy also believes that to attain success, one must have a suitable personality. According to another analyst, “He believes that salesmanship is based on ‘sterling traits of character’ and ‘a pleasing personality.’ But Willy does not have the requisite sterling traits of character; people simply do not like him as much as he thinks is necessary for success.”
Ben symbolizes another kind of successful American Dream for Willy: to catch opportunity, to conquer nature, and to gain a fortune. His mantra goes: “Why, boys, when I was seventeen I walked into the jungle, and when I was twenty-one I walked out. (He laughs.) And by God I was rich.” 
After seeing his father's real identity, Biff does not follow his father's “dream” because he knows that, as two analysts put it, “Willy does see his future but in a blind way. Meaning that he can and cannot see at the same time, since his way of seeing or visualizing the future is completely wrong.”
Bernard and Charley
One thing that is apparent from the Death of a Salesman is the hard work and dedication of Charley and Bernard. Willy criticizes Charley and Bernard throughout the play, but it is not because he hates them. Rather, it's argued that he is jealous of the successes they have enjoyed, which is outside his standards.
The models of business success provided in the play all argue against Willy's "personality theory." One is Charley, Willy's neighbor and apparently only friend. Charley has no time for Willy's theories of business, but he provides for his family and is in a position to offer Willy a do-nothing job to keep him bringing home a salary. (Bloom 51)