It seems that Cammy is wearing spandex that covers more of her legs in this prerelease screenshot. See full preview below:
In the text it also mentions how weird it is that her outfit appears to be changed. Of course, when the game was actually released, Cammy was still wearing her proper outfit. So what's the deal with these screenshots? If we had to speculate, Capcom probably assumed that her normal outfit was a bit too revealing for Nintendo's platform and self censored it. But this was also around the time that Nintendo started loosening their grips on mature games, so Capcom must've been able to leave it in.