"J" should stand for Japan, while "K" should stand for "Korean"; I've met this term a few times and I'd like to know more about the differences on J/K (Computer) RPG.
I am no expert but I believe the fundamental differences between the two subgenres are:
- Lots of grinding
- Technical character builds
- Item based
- Weaker story line
- Strong storyline
- Less about specialised player builds
- Faster to 'progress' your character.