They are both the same age 12 years old
They both had pressures from other people: : Aang to save the world because of his destiny Toph to be over proctected and underestimated do her blindness. Not to mention they both ran from home because of it!
They are polar opposites : :Aang is innosent ,is a nice guy and a bit of a push over sometimes while Toph is Realistic with knowing how society works, is a smart mouth and super stuborn.
Aang was hunted by zuko and many enemies while Toph was hunted by yu and xin fu.
They both invent something Aang invents air ball while Toph invents metal bending.