One of them was written by Games Workshop, and adapted by GDW. Both are small ship universe; neither is consistent with the rest of the adventure line, and they are amongst the earliest printed adventures.
The OTU, a setting into which the addenda, does not truly exist until Suplement 3; prior to Supp 3, each game was in a homebrew setting with some shared assumptions. The OTU itself grows out of the line; it truly becomes THE Official Traveler Universe with later editions incorporating it into the core rules; prior to that point, it was merely increasingly strongly suggested.
Book 0 mentions the star wars connection; Star Wars has the Imperial Senate. The OTU has a representative body: the Moot. Same role, same scope, odds are, same body but different name.