CT had a lot of setting encoded in rules.
MgT explicitly was intended to support the OTU, while not limiting to the OTU. It succeeded on the second, not on the first - there is a lot that one has to ignore in the corebook + HG + Merc to run the OTU using MGT.
To be blunt: MgT encodes a lot of setting into the rules as well - but in some very different ways. Some examples:
CT: No up-or-out policy except in adminstration scouts using Bk 6.
MgT: since promotion and continuance both tie to the same die-roll, in later terms, one is either promoted and retained, or discharged, or in particularly late terms, promoted and forced out.
CT: worlds blocking entry is not explicitly covered mechanically; it can be checked for by rolling against law level (tho' the exact throw isn't given). Still, several adventures presume landing on rather high law level worlds.
MgT: LL has explicit bans upon who may land and how far from the port visitors may go.
CT: Pirates are not explicitly organized under the rules mechanics; only the Pirate career (S4) speaks to Pirates existing in an organized fashion, tho' there are plenty of them in the encounter tables
MgT: Pirate bases are explicit in system generation, but pirates are FAR less common in encounters.
If one isn't modifying (intentionally or otherwise), what one gets from MgT RAW will be quite different from what one gets from CT RAW, even if running the same CT adventures, simply due to various setting elements encoded in rules.
One who knows the OTU from CT will know what to ignore.
It's the little things like this that pretty much force me into treating each edition as a separate canon - rules encode a LOT of setting, and the differences really add up. It's also interesting to note that Marc's canon lists are one edition at a time - he does expect authors to make reasonable efforts to not overwrite other editions, but his public canon lists are one edition each.
I've run the CT setting using TNE rules- needed a lot of small changes (encounters, mostly, but also some differences in UWP encoding, and allowing SS gains.); MGT needed much more obvious ones, despite much closer mechanics overall - Ship encounters, ignoring the right hand column on the LL effects table, not using pirate bases, etc.
Now, I know that many (Esp. Hans) don't really consider rules to be canon - but since they are on the canon lists, I do. And given that much of the OTU is actually encoded in rules rather than setting prose, for CT and MT, it's very much a viable way to find more about the setting - but note that the inferences drawn are not themselves canon, but are canon-derived.
One of the most interesting bits encoded in rules is that the OTU has two different systems of drives. This is because both Bk 2 and Bk 5 are both rules canon for CT. It makes a huge difference if one deletes Bk 2 drives (as I found out in the T20 playtest) especially for small ships. MgT has different breakpoints there, too.
While the big picture remains the same, the underlayment is different in every edition. Which of course means that the serious canonista must adapt the gray in-between to support the big picture if they keep the fundamentals as defined in their edition in use.
Spoiler:
