Not sure about the difference in quality but the major significant difference between Moyes squad and Carlo's squad was that Moyes squad all put 100% effort and desire into every match for the entire duration whereas at least half of our players couldn't be bothered for the 2nd half of the season so much so that most of the time they struggled to even pass the ball to a team mate, let alone try and move the ball forwards quickly and those same players have been doing that long before Carlo took the helm.
We would have comfortably got 4th this season had all of our players put 100% effort and desire in and you could see Carlo's frustration with them in pretty much every single match since Christmas. He has got them well and truly pegged now imo.