As I understand it, US2 uses procedural textures which are dynamic images that change according to the planets' composition, distance from the sun, size, etc. Those aren't still pictures you're seeing. They're not static images that are wrapped around the spherical meshes which is what US1 did. In US1 you could put texture pictures in the textures folder and tell US1 which image to use on a planet. But they weren't "alive" as they are in US2. There were no dynamic clouds, no advancing ice, no molten impact craters, no ocean basins that refill over time as there are in US2.
So those cool textures you see in US2...you can't "get" them. They don't exist in a static image/form anywhere and thus you can't apply them in US1.