I think I can say, with confindence, that the fortifications will be solely the province of CastleWorks Ultimate. I do not know whether ruined versions will be included or not at this point (note, I didn't say they wouldn't...I said I don't know).

SiegeWorks' focus is on the besiegers...those trying to tear down the walls. While a few items will be useful for the defense of the castle as well, bear in mind that this is not where SW's emphasis lies.

As for how far apart they will be...a lot depends on how much/how long the reworking Paul is doing requires, compared to Denny. Bear in mind that Denny was working on Maiden until only about a week or so ago, while Paul's had all of the time since finishing Skull Cove to devote to Siege.

I would anticipate they'll be a fair distance apart, though not as far as originally planned due to the hold on Siege to accommodate all camps.