The first one you can be sure operates under Chinese law and shares data with the Chinese authorities.
The second; my bet is that ByteDance wants to sell it off probably through an IPO on an American exchange. That is why the have hired an American CEO. And that is why they make announcements similarly to Facebook and Google on Hong Kong.
What will happen in Hong Kong? Will all these American social medias be banned because they refuse to follow what is now Hong Kong law?
Essentially expanding the great firewall of China to include Hong Kong ... we will see but my guess is probably not.