China and Russia is basically the same nation. You may see a few differences in them, you could point out how there are small differences you think that are big. But the reality is that they are both nations with powerful army, powerful economy (or at least powerful against the nations they attack) and how no big nation will do anything against them but put sanctions against them.

China could take all of Hong Kong and Vietnam under their nation, like fully, and nobody will do anything about it. Hell I am sure China could much worse, and yet nobody will do anything about it. You think Russia will stop with Ukraine? They saw that nothing will be done so they could do anything they want.