They ARE completely different. Missy is the type that just ignores you until you're in bed then she's all over you. Emmy on the other hand is in your face constantly. As a matter of fact I had the hardest time putting my contact lenses in this morning because she kept bumping into my hand. It's a wonder I didn't poke my eye out. She'll also stand outside the shower door or any door for that matter, and meow, loudly, until she's let in.
So to sum it up
Missy- (now blocking my computer screen, knocking things off of the desk) is the loner of the two.
Emmy-(upstairs with the dogs) is the velcro cat.