They are nearly the same...
Navy is 9mm 226 only, DA/SA, comes with Contrast sights, Polymer Grips, Aluminum Frame/SS Slide, Black HC/Nitron Finish, Anchor Engraving, Anti-Corrosion Coatings, (No threaded barrel version available).
Combat is 45 P220 or 9mm 226, DA/SA, comes with Siglite Night Sights, Polymer Grips, Aluminum Frame/SS Slide, FED HC/Nitron Finish, Flat Dark Earth, Anti-Corrosion Coatings, available in Threaded or non-Threaded barrel versions.
Combats sell for $1,200 ($1,272 with threaded barrel)
Navy is on right now for $1,020
They are VERY similar... but different
Mark