Japanese RPG = RPG made in Japan.
JRPG = A sub-genre of RPG that became popular in Japan. It usually has some sort of turn-based combat, heavy emphasis on story, all the characters have predefined backgrounds and personalities, and it needs to have animu art. Not animu "sprites" as that is usually difficult to accomplish, but animu art. Also, almost no choices to make or your choices don't matter at all.
Dark Souls: Japanese RPG.
Final Fantasy: JRPG.
Planescape: Torment: Western RPG, definitely not a JRPG. It gives way too much freedom to the player to be called a JRPG, from everything you can do and everything you can say, shaping your character's personality.