There are no major upgrades. But there are some minor ones.

apparently it has upgraded the Converters and Mic Pres.
Also added Word Clock
Also added an extra Headphone output allowing you to create 2 separate headphone mixes.

Yeah people who owned 002 said they cant hear difference with new converters and pres... Word clock i dont need, and extra headphone mix would be nice but i think ill go with 002 cos i aint payeing that much money for one extra headphone mix...
than you

Digi-003 has the ability to switch between 2 sets of monitors. I don't know why more interfaces don't have this option!