The HUD looks to be formatted for 5:4 there, but the gravlift and such look too skinny so I'm guessing the 3D view at 1280x1024 is using the same FOV as 4:3. Have you tried a 4:3 resolution to compare?
As for rendering resolution, I'd have to bust out my VGA cable to make a proper guess, but I wouldn't be surprised if they keep the rendering resolution constant and just adjust the FOV. On a side note, back during the Beta I noticed that 1366x768 over VGA gives smaller HUD and menu elements than 720p/1080p, but the 3D view looked the same. I haven't checked the full game, but at least back then Bungie was obviously doing some weird things in regard to their support for various resolutions.
As for rendering resolution, I'd have to bust out my VGA cable to make a proper guess, but I wouldn't be surprised if they keep the rendering resolution constant and just adjust the FOV. On a side note, back during the Beta I noticed that 1366x768 over VGA gives smaller HUD and menu elements than 720p/1080p, but the 3D view looked the same. I haven't checked the full game, but at least back then Bungie was obviously doing some weird things in regard to their support for various resolutions.