@catsalad it's extremely subjective. Broadly speaking there are two types: the ones that move mostly side to side and the ones that go up and down.

I experience magnitude 4 ones a few times a year. The side to side ones might make you dizzy, depending on how long they last. The up and downs jolt you.

Then there are the mag 5 ones. Those are strong enough to make me question whether I should get ready to get out. They make noises (the ground rumbles, windows rattle), the movement is more evident.

I have experienced a few mag 6 myself. Those are strong enough to cause significant concern. The noises are louder, the movement is impossible to ignore. I instinctively reach out for something to grab on. It feels like you are going to fall if you don't.

Mag 7 is something else entirely. I myself can keep composure (as in "not scream, not run") but that's not true for most people. It's violent. I remember being afraid the building might collapse (in places where there's a seismic code, it's unlikely, but possible, assuming the buildings follow it). A short mag 7 is unlikely, so it's not only more violent, it's longer, too.

I've lived thru a single mag 8. That's how my mind imagines war (I don't know, I've never experienced that, but that's where my mind goes). Officially it lasted for 69 seconds. It felt like an eternity. I was on a fourth floor, and it was long enough for us to decide it was better to get out of there and walk down while it was still happening, because every time it felt like it was going to stop, it came back stronger. I guess the uncertainty is the worst part about it.

I hope I never have to go thru a mag 9, but my father did. His description matches those over-the-top movies that look completely unreal. He says he could see the ground opening and closing in front of him. Walls and streets moved like paper in the wind.

I've seen earthquake simulators in museums. While they match the movement, they don't recreate the noises, the visuals and the feeling (you know it's safe).