What is the difference between Ungroup back to original objects layer and Ungroup onto groups layer?
Vectors remember what layer they were originally created on, even after being grouped. If you need to ungroup them, you have two options.
Ungroup back to original objects layer: After ungrouping, the vectors will return to the layer they were created on.
Ungroup onto groups layer: After ungrouping the vectors will stay on the current active layer.