The Windows 10 ISO is stock Windows just as if you had bought a DVD at a store and doesn't include any Surface specific configuration or drivers. Using this it will install then download drivers from Windows Update so the end result is pretty similar but there may be a few settings or tweaks and different wallpaper/backgrounds (I haven't compared them)
The Surface Recovery image will be the same as it was shipped from the factory. Of course it will then do tons of windows updates after installing as well. There may be a couple bundled apps you wouldn't get from the W10 path like possibly FlipBoard, or Drawboard, or 1 year Office 365 depending on what was included in the original configuration.