How are Biff and Happy inverse?

Death of a Salesman is a 1948 drama written in two acts and a requiem by American playwright and essayist Arthur Miller and first produced in 1949. As it covers darker themes such as suicide, lies, identity, betrayal, secrets, anger, misconception of reality, tragic love, and abandonment, the play is considered a tragedy. The play has gained tremendous commercial success and critical acclaim and even won the 1949 Pulitzer Prize for Drama and the Tony Award for Best Play. Death of a Salesman is considered one of the most influential and popular plays of the twentieth century. It tells the story of sixty-three-year-old recently demoted salesman Willy Loman, who lives under the illusion that he is a successful man, and his family, which consists of his devoted wife, Linda, and his equally unsuccessful sons, Biff and Happy.
I believe that the most interesting element of Biff and Happy’s characterization is that they represent two halves of Willy’s personality. Happy is the younger brother who has basically lived the majority of his life in the shadow of his big brother, Biff. He grew up wanting to get the attention of both of his parents, especially his father, and prove to them that he is a good and capable man. Unfortunately, his never-ending need for attention and approval essentially becomes his downfall, which makes his character quite one-dimensional. Career-wise, he might be more successful than his brother and better paid, but just like his father, he continues to live his life through lies and deception, refuses to accept his failures, and is unable to understand his true nature. Happy represents Willy’s entitlement complex and blind ambitions.
In contrast, Biff has always been the favored son, and Willy believes that he can achieve great success in both his personal and professional life, mainly because of the fact that his oldest son was and is very popular and well-liked by many. Thus, Willy wants Biff to follow in his footsteps and become a salesman. However, Biff has no desire to become a part of the corporate world and instead prefers to work with his hands. This leads him to experience a minor identity crisis, similarly to his father, who has spent his entire life questioning and trying to define his own identity. It also makes him jump from job to job, as he constantly gets fired for his kleptomaniac tendencies. Unlike his brother, Happy, Biff accepts the reality and doesn’t delude himself. Biff represents Willy’s vulnerability and sensitivity.
In fact, this seems to be the main and most important difference between the two characters. Biff accepts the truth and even prefers it in the end, and he manages to use his potential and change, while Happy (and Willy) choose to live out their lives in delusion, blinded by their own ambitions, egos, and false sense of importance. The only things that might connect the two brothers and their personalities are their big dreams and aspirations, their blatant selfishness, and their love and support for one another.