The people who participate in sit-ins are IDENTIFIABLE. It's often the whole point that you show your face and identify yourself as an aggrieved party.

Furthermore, lots of those folks get arrested. It's exactly the point that you force the state to take you into custody and deal with you as a means of overwhelming them with otherwise law-abiding citizens.

SO...I don't agree with your assertion that it's the same thing. It's a manifestly different thing.