Stallman is like you would imagine him. Hardcore geek/guru, fully involved and dedicated to his cause.

Torvalds is more of the pragmatic kind of person in personality (at least from what I remember reading about him over the years). He's not a preacher like Stallman, and actually much less "only linux is good, the rest is garbage" than most of Linux gurus.

And I guess it is apparent in the look as well. One "hardcore", the other more pragmatic, "normal".