Models are fairly generic placeholders, attractive men and women who anonymously walk down the runway at a fashion show or stand up for a photo shoot. It’s surprisingly unglamorous and isn’t particularly steady or financially rewarding.
Supermodels, on the other hand, are a relatively recent innovation, and they are in a totally different (financial) category. The interesting thing is that everyone benefits: the model makes a lot more money, the advertiser gains more credibility from using the known face and the audience gets the frisson of recognition that comes from celebrity. Supermodels aren’t necessarily prettier, they’re merely more famous, a niche that serves all the parties.