It was a port. It had a save system that wasn't the best, and the only other difference I can remember was that it had one other gang which wore red , and dropped a lot of money and carried longer chains. The graphics were a little sharper too.
The controls were different, with a tap or press for attack. Also, the game incorporated all the moves from the Famicom game Downtown Special: Kunio-kun no Jidaigeki Dayo Zenin Shuugou.
After you beat the game once, it also incorporated the boss-join mechanic from Shuugou, where other bosses can join you. However, it's implemented different than Shuugou. This is how the game should be have been from the start, and it's interesting how it's calculated. For instance, if you over-use certain attacks or hit a guy while he's down some bosses may not decide to join you while others will. Along with the calculation you have to meet certain action criteria such as defeating/befriending/visiting certain people. That's where replay value comes in. There are FAQs out there which show the specs.