I recently ran across this nice summary of the differences between Japanese and Chinese acupuncture. These are general differences. Please realize, though, that there are all types of acupuncturists in Japan, many of whom do a "Chinese" style. And then there are "mixers" like me, who lean toward one approach but incorporate both. In fact I would call my approach "American Eclectic" in that while I am heavily influenced by Kiiko Matsumoto Style acupuncture and more recently Tsuyoshi Shimamura, I also will use Medical acupuncture, Dry Needling (a misnomer by Physical Therapists trying to skirt real acupuncture licensing), and TCM, which is the current most popular form of "Chinese" acupuncture. Oh, let's not forget Master Tung style which is also very interesting!
But here's the article: 7 Key Differences between Chinese and Japanese Acupuncture