These two features are both employed in the same way: Select the object that you want to mask or clip, then the object that will serve as a mask or clip, which must be positioned above the first object. Then use Object > Clip > Set or Object > Mask > Set. The top object will then hide parts of the bottom object.
The two features do not result in the exact same image, though. The clip allows you to hide all parts of the bottom object that go beyond the contours of the clip object. The colors of the mask object affect the opacity of the bottom object.
There has been error in communication with Booktype server. Not sure right now where is the problem.
You should refresh this page.