In the Peacock's popular show Modern Family, which showcases three generations of a family and how they deal with modern-day problems, every episode ends with a beautiful message about what love means in these modern times. Alex and Haley Dunphy are two sisters who reflect a chaotic yet relatable sibling relationship, which is comic at its best and also heartwarming.
They couldn’t be more different in personality, priorities, and how they interact with the world. One of the scenes perfectly reflects their difference when, during a fight, Haley says that she wishes Alex were not born, and Alex argues back that they (the parents) wanted someone with "brains".
Here's a detailed breakdown of how Alex and Haley differ.
Here is how Haley and Alex from Modern Family are contrastingly different

Alex Dunphy, played by Ariel Winter, is the "brain" of the family—exceptionally intelligent, academically driven. She is often portrayed throwing sarcasms at Haley, which she can't decode. She lacks social skills and is rarely seen dating anyone.
Haley is a social butterfly. She is not book smart but emotionally intuitive and socially savvy. She finally finds her career in fashion and business after living in the basement with her family for a long time. Throughout the seasons, she is seen dating several guys, leaving Alex in awe of her social skills.
There is a huge difference in how both the characters dress, despite being from the same house. Alex dresses modestly in comfortable T-shirts and pants, while Haley is much more stylish and trendy. She knows how to make heads turn just by her appearance.
Alex prefers staying at home and getting into her book. She doesn't even like parties. Haley loves shopping and social events. She initially appears superficial in the show, but then matures significantly.
How the character arcs of Haley and Alex end in Modern Family
In one of the scenes, when Alex got promoted to a higher standard math class and began sharing a class with Haley, the two sisters came home after a cat fight and urged their mother to separate their schedules. Haley is embarrassed by how Alex provoked the professor to give homework while Alex points out how Haley said 8 is a "prime number."
Claire (the mother) very cleverly manipulates them to be "super Dunphys" and tells Alex to tutor Haley while Haley can help Alex with her social skills. This actually makes both of them think of the perfect exchange they can have in the class, appreciating each other's skills.
Despite all the differences, the two sisters realise each other's importance. Alex, though, starts as a know-it-all and ends up realising intelligence alone doesn’t guarantee happiness. Especially after facing burnout, social anxiety, and loneliness in college.
While Haley starts as immature and carefree, she later becomes responsible, especially after becoming a mom. She discovers her strengths in the creative world and builds confidence in her abilities in Modern Family.