The 2050 motors I believe have a different style of stator wind which makes them very torquey compared to the 1900kv. I believe the can is a bit longer as well which makes them difficult to fit in some buggy chassis. The 2050 motors I understand are designed for Truggy and 1900 for Buggy.
Its been a while since I ran eBuggy and eTruggy but that is what I remember is the case.