So what's the difference between "curvy" and "a few extra pounds"?

Curvy is being more thick in the hips and thighs area and usually the chest area, although sometimes all features don't come together. Having a "few extra pounds" is basically being chunky. Honestly if a girl presents herself on a dating site as having a few extra pounds then I'd take the hint that the girl is trying to say that she has extra fat which isn't always attractive to some people and she's just trying to make it sound better to whoever is viewing her profile.

There is no specific definition of "curvy", so to some people, it does mean "a few extra pounds". I think some girls use it because they think it sounds nicer than saying they have excess weight. Most people wouldn't want to admit that they're overweight, and women are especially sensitive about their bodies, so they sugarcoat it. I don't think they're intentionally lying though.

I personally try to avoid the word "curvy" since it has multiple meanings.

Girls can be really insecure about their weight and see it as a turn off for me to admit they have a little extra weight...