I would like to explain it in terms of Illustrator and Photoshop features. Maybe you'll get an idea.
See this image. Suppose you want only a certain part of star. So you use Object > Clipping Mask > Make feature. Here the word used is mask, but on very right side you see the desired output, i.e., a portion of star. The square object is still there, but now it's acting like a boundary/fence there. You can call it a clipping path.
The following is a feature called Vector Mask. Using it, you can perform a similar action. Just create a vector mask, and select the desired area with pen tool.
You can see a white colored polygon in layer panel. It's vector mask. And you can call the path as clipping path.
Note: In Photoshop, rasterize the circle object before you apply vector mask.
For example, in the image, I don't want the mike, so I can use the Vector Mask feature (to remove the mike. You'll need more Photoshop work to make it perfect).
Sometimes you can use this feature to remove backgrounds, but for that you've to be good at pen tool.