Vector Overlay: intersect, clip, union, difference

How do we make vector files interact with each other? When two vector files sit-on-top of the same area, we can use overlay commands.
Minute Markers:
1:25 Intersect.
2:42 Clip.
3:24 Union.
4:56 Difference.

[@parhamfathi.hafshejani4271]

awesome .. you describe things very clearly. thank you

[@utubemania9079]

Very nice explanation

[@FANTICOUS32]

The intersect schema is wrong