What are differences between Maya blend shapes and UE morph targets?

In Maya there are pre-skinning / post-skinning, object space / tangent space blend shapes. Which ones are implemented in UE for skeletal meshes?
I have the impression that only pre-skinning object space blend shapes works the same in maya and unreal. Is that right?

I tried to import post-skinning blend shapes in various ways but it never worked correctly. I even have the impression that they are not supported by fbx.