On the surface, the two couldn't be more different. Aunt Alexandra is horrified that Scout likes to wear pants and just doesn't act properly in so many ways. Aunt Alexandra is all about custom and maintaining a certain image and doing everything right in terms of other people's opinions.
But underneath it all, both Scout and Aunt Alexandra are willing to recognize hypocrisy and to challenge some things when they are really pushed into a corner. For Scout it happens more often, perhaps because she is more of an impetuous child, but Aunt Alexandra also shows her willingness to do so when she stands up to her missionary group by calling them out on their hypocritical attitude towards the black members of their town and the people they are trying to "save" in Africa.