In Death of a Salesman, how does the relationship between Charley and Bernard's relationship create a contrast to Willy and Biff's relationship?

This is an excellent question because through it you are
identifying how Miller has created a separate father-son relationship to act as a foil for the
relationship between Willy and Biff. In a sense, Bernard and Biff's relationship parallels
Charley and Willy's relationship. Bernard helps Biff academically with his Maths, as his father
helps or tries to help Willy financially, by giving him money and then offering him a job. Both
Bernard and Charley try to make Biff and Willy respectively face the realities of life. Bernard
is always encouraging Biff to study harder and plays almost a father-like role, telling him he
shouldn't drive without a license. Equally, Charley tries to get Willy to face the realities of
working life. Ironically, in spite of the way that Willy talks about Charley and Bernard, because
of their "unmasculine" traits, it is Charley and Bernard that are the success stories, with
Bernard becoming an incredibly successful lawyer.

Another central
difference that is reinforced through the comparison of these two father-son relationships is how
Charley never dwells on misfortune - he is a very down-to-earth and decent individual who is
intensely realistic and practical. Willy, on the other hand, is always talking about what could
have been rather than facing the reality of what has actually happened. According to Charley, he
owes his success to the fact that "I never took any interest in anything." Bernard and Charley
both fail to understand the importance of dreams to Biff and Willy and how their dreams sustain
them and give them hope. Unfortunately, it is only Biff who at the end of the play is forced to
become more like Bernard and face reality for what it is, rather than living a life deferred
waiting for dreams to become substantial.