I had the J3. There have been a lot of technological advances since it was introduced. There are far too many differences to attempt a comparison. The N3 has quickly become my favorite player. I use it with iems, buds and headphones. Unless you need the smaller form of the J3, I don't think you would be disappointed with the N3. I should add that I find the UI of the N3 far more user friendly than that of the J3.