As far as I know the characters do not differ from one another (in terms of gameplay) and are not intended to.
So you might have noticed it in Living Daylights mode where the ones carrying flags are supposed (I guess) to be a little faster than the rest.
For anything other than that: you might have come across different players using these skins that were more agile than the other players you saw, moving more directly, so you got that impression.
Note: that's mostly the ones that have been around for some time and know exactly what they're doing, not hesitating a second, like most newer players do.