That is one of the things you have to really watch out for with SIG NH is model overlap and actual build.
I got a great (not asked for) P226 education through the SIG custom shop a few years ago.
The P226 NAVY, MK25, and Combat are close but not the same. The original NAVY (which is now missing) evolved to the MK25, which is a combination of the NAVY & Combat models. The old NAVY did not have the phosphate internals and mags (but it could have, as it was a case by case basis ... SIG quality at its' finest). The Combat model always had the phosphate internals (but again, some did not get it you have to check them closely when you open the box. Surprise!)
The new MK25 is supposed to have everything the Combat provided and a cool "Anchor" (like the old NAVY model)with a matrix ID badge. Also, the MK25 is supposed to have the double roll pin for service, which oddly the combat did not (but may have).
I think it was stated above something about a chrome lined barrel ... if you have one of those in a P226 it is a one off "Collector's Gold" as SIG has not chrome lined any of the stated models but they have phosphated the outer barrel.
Hope this helps some of the confusion before you buy a new P226 in any of these stated models.
NOTE: You may also ask for a threaded barrel option with the Combat but not the MK25 ... which seems very odd.