Themes?

[xandra panda]

There are four themes, European, Boreal, Temperate, and Tropical. European gives itself away, but what are the other ones. Tropical is also kind of a give away(ish), but I'm wondering if Temperate is the American theme, and what is Boreal?

[grapplehoeker]

For assets you have 2 sets, the European theme and everything else.
The other difference between the 4 themes has more to do with the lighting and map topography than actual assets.
When creating your own maps, you'll want to decide upon a theme to use. So, if you want a sunny island/shorelined city with beaches, then Tropical would be a prime choice. Whereas mountainous high altitude cities may look better with a Boreal theme.
You can also change the lighting on any given map so you can view the differences to the appearance each themed lighting can produce to help you decide. You can also subscribe to several lighting mods (LUT's) from the Workshop.

[napiercpt]

You get different trees for each one too e.g. palms for tropical, or pine trrees and conifers for boreal.

[xandra panda]

I'm talking about the buildings though. Do the residential things and such change their looks?

[napiercpt]

Boreal, temperate and tropical share the same buildings.

[grapplehoeker]

Originally posted by BVD #FallOut4:

I'm talking about the buildings though. Do the residential things and such change their looks?

Residential, commercial and industrial buildings will all change in appearance as they level up and 'grow'. The architectural styles used have been documented in the Archtectural Artbook that came with the Deluxe version of the game.
Specialised industries only have one level so they do not change.
European high density buildings do not become high rise/skyscrapers.