They're all 18650 cells at heart. Your Milwaukee Fuel drill and impact have brushless motors, probably with higher capacity batteries (measured in Amp-hours) than the Ryobi set, which have brushed motors and probably 1.5-2 Amp-hour batteries. There are plenty of power tool review blogs that do tests to see how many fasteners/board feet/etc different brands do with the same capacity battery packs.

FWIW, Milwaukee and Ryobi are owned by the same parent company, Techtronic Industries