To define those two things: pitch is a measure of the relative highness or lowness of a note. If I take a fundamental note, I could make it higher or lower. However, resonance is a measure of brightness or darkness of a fundamental note. If I pick one note (one stable pitch), I could make that note brighter or darker.

Most people, when they're modifying the perceived gender of their voice, want to be working a lot on resonance. That can sometimes hard to do if you're unable to distinguish those two things because the brain sometimes hears brightness and darkness as highness and lowness, which is normal (and why working on resonance is so effective!)

If you're struggling to differentiate those two things, an exercise I like is to isolate pitch by talking like a robot on a single pitch. If you want to work on the brightness of your voice, you can do so by just having one pitch only and trying to make it as dark or as bright as you can without changing the pitch at all. This can help you to isolate resonance so that the pitch is stable, and you're only working on that one characteristic at a time.

If you like this, there's much more information in my course, Trans Vocal Exploration. I hope this helps!