Hm, the 1st, 3rd, and 4th pictures are definitely the same location, but the 2nd? I don't think so. The only thing 2 has in common with the others would be snow-topped mountains in the background. The design of that building just doesn't match up with the more medieval-looking castle.
Maybe 1, 3, and 4 show Weisshaupt Fortress and 2 is actually the Inquisition's headquarters? Or could these different locations be two of the Holds the Inquisitor can take over?
Yeah, I'm totally just pulling stuff outta my arse on this one. Anyone's guess is as good as mine at this point. 
Maybe it's a different concept of the castle. Consider that in the fourth there's the female dwarf Inquisitor along with baldy elf and Cassnadra, and that the name of the concept is 'A new Home'. It doesn't leave much to interpretation. Beside, we won't visit Tevinter in DAI, so I doubt we'd go further North in the Anderfels.
Another concept that might show a different concept of the castle is the 'Coronation', concept, since it'd still based on the Frostbacks mountains.