Id divide more by the type of track rather than the theming. It aint perfect

Race Track- basically courses that look like ‘purpose-built’ racecourses, the circuits, the stadiums, the arenas etc,

Off-road- Tracks that predominantly drive on non-asphalt ‘natural’ courses, including snow, sand and dirt.

Street and Urban- This is a bit broader but would be generally anywhere in a built up area that would not be typically designed as a track, so city courses but also things like the subway, airport, electrodome, coconut mall.

Special- Non standard tracks that dont neatly fit into the above criteria and are generally a bit more ‘fantastical’ like Ribbon Road, Music Land, Tick Tock Clock etc.

Rainbow- I guess these would count as specials but the Rainbow Roads themselves are so iconic they can have their own category lol.