I have 4 V5’s, a V4, and a V3.1.
I know there are some subtle differences between the 3.1 and 4, but they aren’t that different overall. If I recall correctly, the biggest difference was the availability of different Saturn can/Phantom engines, and minor Sealab parts…so one could build a more specific x-wing. Red 2, Red 5, and such. Started with V4.
I think the major differences between V3 and V3.1 was some changes to canopy area, but not 100% sure.
I know that the V5 fuselage is a little bit wider than the V4, and has some other small dimensional changes.
The hollow ‘hero’ wings are the biggest difference. When I ordered my V5’s from Mike, he asked which ships I was building, and supplied parts for those specific models.
Someone more knowledgeable will probably correct me.