The M25 and M25XP engines are different
horsepowers, essentially the same 3 cylinder engines, but the XP has more HP, has the newer alternator bracket standard and the 3 inch HX. They are NOT the same engines, although to the untrained eye they seem to look alike. There are also a series of XP and XPBs, maybe even with an XPA in there somewhere.
It is a common misconception that the M25 stands for 25 HP. That's still just plain wrong.