Higher values in Col A than Col B, sum rows with the higher value and show difference

Hi Community,

I have two columns of values, I need to know the sum of all the rows where Column A has a higher value than Column B.
If Column B is higher then ignore.
There could be 100+ rows of values and I need to apply this to multiple workbooks, but each workbook will have it's own total.

Any help is appreciated.
Thanks.