The 930 is a mountain bike made from butted cromoly and it was Trek's entry level enthusiast bike I guess. IIRC they were STX or STX-RC equipped which is equivalent to the current Deore components. They were available with front suspension sometime in the mid to late 90s. Before that, the fork is rigid.
I think the 8xx bikes are hi-ten steel, possibly cromoly, and they were the recreation level bikes.