this one looks like it was done with an eps file of the land outlines which was extruded then Wrapped into a sphere. It’s hard to be so smooth in the outlines otherwise with a large number of polys – doesn’t mean it wasn’t so though. It’s easy to do a single layer land mass earth with textures but extruded like that…
i don’t know where to get such a detailed eps of the earth but the general concept is easy enough. Otherwise with textures (alpha and displacement) this is the sort of thing that’s possible. Even with a biggish texture the edges are still a bit chunky… which is why I think that one is an eps/ai file extruded (or something like that)