Differences include:
-The opening. The 1976 version opens with the credit sequence, in the style of an Asian movie, and then cutting to Cosmo following a loan shark to the back. The 1978 version opens with the "it'll pick up" scene, then cutting to much more western style opening credits, and then showing him arriving to meet the loan shark
-The 1978 version removes all the stage performance scenes, which accounts for at least 15 minutes of the movie
-The 1978 version includes an additional scene showing the gangster extorting a couple before they see Cosmo.
-In the 1978 version, Cosmo's meeting with the gangsters is extended. This is where we learn Cosmo was in the Korean war. It also explains why Cosmo is out with the girls in the next scene.
-The 1978 version cuts out most of the bits involving Cosmo picking up the girls to go to the club, including meeting with families and talking to one of them in the limo.
-The 1978 version cuts out an early scene of Cosmo in the dressing room with Mr Sophistication and the girls.