In theory R32 is supposed to be a little more efficient than R410A as a refrigerant so that might go some way to explain some of the differences between these two machines and their quoted efficiencies.
Thing is, how they are run in the real world makes all the difference and quoted COP figures vs real life are always going to be a bit different. Nobody lives in a humidity controlled thermal test chamber!
What I would say though, as you’re looking at split systems, they have a very slightly higher chance of a refrigeration leak in my opinion than a monoblock air to water system. If a refrigeration leak occurs, it is better to leak out R32 into the environment than R410A. A fridge leak is very unlikely to happen but worth a thought perhaps.
I don’t think enough attention is paid to the GWP of different refrigerants. I know there’s a move to use Propane R290 in some new monoblock air to water machines. A GWP of only 3! Might not be seen in split systems for a while yet.