YES, there is a big difference. You cannot unlock all the characters in the JP version simply by playing and completing challenges on your DC alone. It required trips to the arcade (in Japan) with your VMU in order to do so.
However, there are plenty of save files out there with the complete roster unlocked. Getting your DC online and downloading a file is the best option. Now, if you have broadband internet at your house, you'll need a broadband adapter for your DC to complete this task. There are probably other methods to get a save file onto your VMU, but they most likely require an additional hardware purchase as well. Someone feel free to correct me if there are other, cheaper ways to get saves to and from a VMU.
Also, the JP version definitely has the "Take You For a Ride" track. I only had the JP DC version of this game for years and years, and that's the only way that I even know that track (I picked up a PS2 version a couple of years ago, but haven't ever played it).
