Danzauker said:
Yeah, that works too. It's not a direct comparison, as another posted pointed out that your Fly and Teleport spells are still given to characters at levels 5 and 9.
Basic (1-3): Dungeon adventures, and just learning the rules of the game. No game world setting included at all.
Expert (4-14): Wilderness and city adventures (and more dungeon adventures). The boxed set included a map and sketchy information about several countries in a fairly small and contained geographical area.
Companion (25-25): The focus shifted towards founding and ruling a dominion, and adventures that weren't so focused on killing things and taking their stuff. The "Known World" has now expanded to include an entire continent, with highlighted areas on the included map showing where the "Expert Set" world was located (as well as a couple of expanded areas for X series modules). The first CM module (Test of the Warlords) introduced a massive new frontier to the north where it was intended that players would stake out their own realms. We got 7th-9th level spells introduced for the first time, as well as something similar to "Paragon Paths" for some characters; wandering Fighters could become a Paladin, Knight, or Avenger (depending on alignment), and wandering neutral Clerics could become Druids.
Master Rules (26-36): The focus here begins to transcend the management of earthly territory, and now the quest for immortality comes into the forefront. The boxed set details four paths to immortality, and the adventure modules deal with truly epic events that all play back into the paths to immortality. The "Known World" presented in the boxed set now shows a map of the entire world. The "Weapon Mastery" rules introduced here try to make every weapon feel unique, though I'm not sure why it was included so late in the series, but it looks like 4e is borrowing some of this too, at least for Fighters.
Back in the day, this was a pretty awesome progression, as each "set" of levels felt different (if not mechanically but thematically), and the adventures supporting each set tended to reflect the focus of their respective boxed sets. I always missed that feeling after "upgrading" to AD&D.