[VBA] Comparing two columns and pasting the difference into a third column

I'm trying to compare two different columns of products and pasting the different into a third.

If there's a product in column A but isn't in column B. It will show in Column C.

Example:

A | B | C
----------
1 | 2 | 1
2 | 3 | 2
3 | 0 | 0
4 | 5 |


I've just started to pick up VB recently so I'm still a beginner. Any help would be appreciated. Thanks