The first thing I hear when I introduce my 4 year olds as twins is "Are they identical?" Now, really what do you mean? Do they look alike? I guess in a way they do. They don't really look much alike to me but I guess to strangers they do. Do they act alike? NO! They are as different as night and day. Caitlyn, the older by 20 minutes, is a tomboy. She loves wrestling most of all and wants a car bed. Charlee, the younger one, is a girly-girl. She loves dresses and princesses and even claims to be a princess. Sometimes she'll do the rough and tough playing, but mainly she's the "Oh, no! My hair is messed up!" one. Do I dress them alike? Majority of the time, no. They both have their own taste and choose their own clothes.
Caitlyn and Charlotte
Now, the younger set of twins, age 2, even look as different as night and day. It's hard to see in the picture (below), but Cheyenne has dirty blonde hair and Courtney has dark brown hair. Cheyenne wears a size 2T-3T and poor little Courtney doesn't even have the waist for 12 months yet. Cheyenne is the lovey-dovey Mama's Girl and Courtney is the "Don't touch me unless I come to you" one.
So, honestly, twins does not = identical. They are each their own little person.