Never used a VP, does it have a governor?
Maybe, maybe not, that's a part of the training. A CS prop is a VP, but not necessarily the other way around. There were (though in 40 years I have never seen one) hydraulic variable pitch props, which were not governed. There are now electric VP props, for which the pilot must manage RPM.
An important element of differences training for any not FP prop is the fact that loss of pitch control or governing is possible, and what action the pilot must take. In my opinion, differences training should also be required for reversing propellers, but they have not made the list yet. There are many things which should be understood with those, and their differing methods of operation.
From BossEyed's EASA list, I had an amusing discussion with the staff of the Norwegian CAA on this topic, as I was flying an EFIS single piston amphibian in Norway. At the time, it was Canadian registered, so within my privileges. When we discussed training (differences training) for the Norwegian pilots of this aircraft, the CAA pointed out that having the required signoff for EFIS on a SEP landplane would not carry over to the seaplane, and according to EASA, the differences training would have to be done again in the seaplane. Even before I told them my opinion of the silliness of this, they conceded it sounded odd, but that was the way the rules are written!
It's always a great idea to get training on a system new to you...