One or two players can team up as Bub and Bob throughout the entire game.
Bubble Symphony is the official Bubble Bobble 2 (replacing Rainbow Islands, which was also called Bubble Bobble 2 much earlier on). It plays just like the original arcade game, but with beautiful graphics and sound and new branching paths and secrets.
The Saturn version is a port of the arcade Bubble Symphony. It was published by Ving in Japan and never released in other countries.