Imperial stations are different on the outside - they have a blue-themed paintjob (or cyan-themed light scheme, in the case of Coriolis stations). And the name of the station is painted on the entrance ring in big, bold, seriffed Imperial font.
Compare this with Federation: Red colourschemes, and the station name in tiny font just above the mailslot with the FSP (Federal Star Port) number in big, bold lettering on the ring.
As for the insides, these are determined by the wealth and economy type of the station, rather than the owner. Of course, a Superpower-owned station has lots of banner advertisements up, proclaiming the virtues of their union. But that's the extent of superpower alterations.
In this modern era, space stations can change hands fairly rapidly. Slapping a new logo and paintjob on a station which has changed hands would be a fairly quick job - actually altering the structure would not.