It's about the technique of the tackle. Xhaka enters with more control, yes, than the Burnley player, but it's simply not a situation/technique of tackle that's going to create real danger, whereas Xhaka's is. That's demonstrated by that type of tackle being about as reckless as it can be but no real harm coming to Özil. Take the same type of tackle that Xhaka did and put it at that intensity, and the player ends up like Ramsey against Stoke.
It's a problem with coaching, as well, tbh, because it's clear Wenger allows this kind of tackle from his players...you need not look further than Flamini who made a tackle like this every game and continued to be played. A good manager should see that in training once and say: never again, or I fine you. It's really pretty simple.