What is a "Valid" watch hour, and why is it so different from my analytics page?

My gaming Channel just hit 500 subs and my yearly watch time in the analytics is at 3200 and counting. But in the earn tab it is just under 2300. Why is this? Do others have the same issue? And what is a valid watch hour? So my shorts or live streams not count towards my "earn" watch time? Thank you in advance. (Gaming with Mac on the Mic)