First, the ship line is more modularised. While each individual ship is still a work of art, the internal components and systems are more consistently arranged to aid non-Mon Cal techs who must work on the ship. Second, all the controls and displays have multiple wavelength settings so that crew members of any species can crew the ships (the original MC80s had displays designed specifically for the Mon Cal's viewing wavelength, meaning the Human and other alien crew members couldn't read vital information).

The 90s have increased drive, manoeuvrability and shielding systems, as well as many more weapons. Naturally, the ship has an upgraded power generator system to handle the increased power demand. Finally, the ships have more interior cargo space, allowing them to carry a full 72 starfighters (2 wings), making the MC90s the equivalent of a Star Destroyer in terms if fighter compliment. The first of the MC90 line is the Defiance, which now serves as Admiral Ackbar's flagship.

Sources:Horne, Michael Allen. Dark Empire Sourcebook. West End Games. June 1993