Why is pain different when coming from different sources?

I was unbraiding (my spellcheck says that isn’t a word, but… I’ve definitely heard it before) my hair a few days ago, and my mom was helping me. It hurt a lot when she would unbraid some of the braids, but when I would do braids, it didn’t hurt as much.

Why is this, when it’s the same hair on the same person, just another person inflicting it?

And no, she wasn’t pulling harder in the least bit. If anything, I was pulling harder than she was.