Well, elves are a longer lived race, more closely connected to magic, tend towards a slighter, lighter build, ethereally attractive. And culturally, I could go on for a while, but that's not really what your asking. But they are off a totally different descent from humans, and while they can interbreed, it's not very common. And their offspring are usually a nice combination of the two, but both sides often mistake them for the opposite.

In a very, very condensed example, we're like wolfdogs. Not one or the other, but a combination of both.

[She almost used mules as an example, but could easily see a future of being referred to as such. No thanks.]