This is something I discuss often with students. I end up explaining it when I visit other schools, because most students take an inordinately long time to understand there are many kinds of resistance:It depends on how its done. I once had a white belt Taekwondo student come up to me and complain that she wasn't able to practice her hand grabs on her son, who is a black belt. He knew what she was going to do and applied all his strength against that motion. She said she wasn't sure she was doing it right if she couldn't use it on him.
I explained to her that she wouldn't be able to. What she would do, if she knew more techniques, is to go the other direction. If your attacker is preventing you from going across their body to break their grip, you go around their body. However, she hasn't been taught that yet, and shouldn't be expected to know it. Heck, she hasn't even been taught the techniques that go in the other direction! At her level, she's learning pieces of the puzzle that will come together later. Her son, the black belt, should have been using passive resistance (make her have control of the technique, but don't fight her on it), because she's not yet ready to figure out those transitions and modifications to make it work.
- full resistance (fighting back to prevent a technique and apply your own)
- passive resistance (giving a fairly "normal" response in the situation rather than just standing there like a grappling dummy - continuing the thing you were doing when they started the technique)
- false resistance (doing something that only makes sense as a dojo counter to the technique (locking both arms and your upper body so you're immovable, for instance)
- counters (these can be part of full resistance, but can be practiced separately)