What is the difference between a delta 7b Jedi star fighter and a delta 7 Jedi starn fighter

The Delta 7 starfighter was a prototype that had a built in astromech droid, which made for a thinner ship but the droid couldent be removed. The Delta 7b was the sucsessor to the the delta 7, and had a bit thicker of a cockpit but had an astromech port, allowing the droid to be removed