GA remarketing list vs. AdWords remarketing list
More important is to work out who's buying, how much money you're making and where it's coming from! After all, you have control of the front end (your ads) and the back end (your company's sales and profits). Look to those and what comes in between will help you improve the things that really matter.
Does this help?
Just to add to the answer above here is what i have understood from my experience.
This mainly happens because Adwords and Analytics use 2 diffrent type of cookies. Analyticss uses 1st party cookies and adwords uses 3rd party cookies. Under secured networks especially in finance and IT companies some companies will have browser settings to reject 3rd party cookies.
This leads to discrepancy between these to list sizes
Hope this helps