The "Continuing Mission" schematic is apparently a very, very rough sketch cut-and-pasted from Galaxy class Okudagrams - probably on Okuda's Macintosh when Greg Jein or Rick Sternbach asked him for a drawing where he could play with new ideas for the upper pod. The schematic is seen in "Redemption", but a ship corresponding to it is never seen. Apparently, Okuda had no 'grams on the real Nebula model even after its appearance in "The Wounded", so he threw together this rough approximation when needed. Later he probably worked out a proper 'gram, although I think no such 'gram was ever seen in any episode.The "BoBW" Nebula study model is very similar to the schematic, especially in its final incarnation where it receives the triangular pod for an appearance on Sisko's tabletop. But it has the nacelles where they should be in all Nebulas, not mounted low as in the schematic. (No, the nacelles are not detached from the hull for better portrayal of secondary hull in the "Redemption" schematic. They are simply mounted on too long pylons.)
So if we accept all the schematics and all appearances of the various models, we now have no less than eight Nebula variants!
-"BoBW" study model with two tiny extra nacelles, then with those nacelles merged into a rollbar for faking a Phoenix tabletop, then with triangular pod for DS9 tabletop (that makes 3)
-USS Phoenix photo model (adding to 4)
-USS Sutherland photo model, plus her incorrect monitor schematic (that makes 6)
-USS Farragut, a refinement of the Sutherland model for silver screen glamor (we're up to 7 now)
-the CGI bastardization of the Nebula class (a total of 8)
Timo Saloniemi