I played TrackMania long before it was available on Steam. I'm unsure but I recall it having a different map editor and different tiles than the current free version, TrackMania Nations Forever. How do the two versions differ, specifically in gameplay and maps?
Trackmania has a pretty unusual release/upgrade path, where three games have become 1 game with a demo.
Now we have three different trackmania games, and here is where it gets unusual.
As the codebase, including the shared stages and the networking code between the games is now the same, TrackMania Nations Forever is now nothing more than a demo for TrackMania United Forever and TrackMania United Forever includes everything that is in TrackMania Nations Forever.
(afterwards, there was a contest and corresponding free update, which updated it to TrackMania United Forever: Star Edition )
So effectively, the trackmania now availble on steam, is an updated re-release of the previous trackmania games all together.
TrackMania Nations Forever consists of a single stage (Stadium), first seen in TrackMania Nations while TrackMania United Forever: Star Edition consists of all stages of all the previous Trackmania games.
More information can be found in the Trackmania Wikipedia Article