This is an expanded version of Jets'n'Guns which features several improvements to the original game.
The main enhancements are the increased screen resolution of 800x600 and the replacement of the text-only mission briefings with comic screens.
Other changes include 21 new levels in the main campaign (the original only had 21) with 70 new enemies including 16 bosses. To fight those you've also access to 7 new ships and 17 new weapons. There are now also secret levels, items and ships waiting to be uncovered.
There's also a new rank system where you can earn additional money and win medals depending on how good you have been in the mission (killed enemies, secrets found and so on).