What's the difference between static waterfalls and movable static waterfalls?

The static waterfalls appear in level 1 LOD, the movable static ones do not. This lets you pick and choose which ones you want to have LOD and which ones you dont.

I personally wanted more LOD, so I made a new form of the static ones and enabled LOD all the way up to level 3, so they now appear even on my map.

but static waterfalls doesn't simulate water current while movable ones do. So if I want to have waterfalls with LOD won't I have LOD for them and vice versa if I'll have waterfalls with current I won't have their LOD?

Static ones simulate current as well. Both will sweep the player over the edge to their potential doom.