I fail to see how bigger tits and surviving until the ending make Tifa any different from Aeris. They looked different, had different Limit Breaks, and one of them died. Those were the only differences. Aeris may have stated her feelings for Cloud, but she never acted upon them. She treated Cloud like "that guy that I really should date, but that for some reason I don't want to." Tifa did damn near the exact same thing, only in a more subtle fashion. They were the same character.