OK. Tifa's kind of dense, Aerith's...well...kinda like Rinoa in a sense that she can actually say what she feels. I tried doing that horrid pick-up line on Tifa the morning after when we were about to raid another Mako plant and she's coming along for the ride (you know when you can choose a reply to her good morning routine?!). Damn!
Other than the fact that Tifa was modeled after Lara Croft and Aerith looks like Sephiroth's younger sister AND one of them dies...these 2 young women are as different as night and day. You can't get any better than that!