The other factions zones in veteran content are completely different instances from the normal faction zones. All enemies are scaled up to veteran levels and both resources and lootables are in general scaled to whatever that area's veteran level is.

The time it took to get to 1-45, add it twice over and you get the VR ranks :P Not only that, the VR zones are harder, much harder than Coldharbour, each mob has 2-3k health and you get into scenarios where you have to fight several of them. If youre a light armor sorcerer type like me, the power attacks of the sword fighters can one shot you or cripple you extensively. Fighting more than 4 mobs means death.
The VR dungeons, unlike the normal dungeons, are more like a raid difficulty if you compare to WoW. You need tactics, coordination and communication, not only that, you need to be a good DPSer, healer and tank to even have a shot, not like the normal dungeons where 4x DPS could beat it.
Youre in daggerfall? Get ready to kill Covenant soldiers in Aldmeri Dominion (because *** story :P). And you will only see other Daggerfall members who are VR rank, no communicating with any Aldmeri, you are instanced somewhere else than them and thus you only see DC members and fight VR mobs with VR loot and VR crafting.
Getting from 49-50 requires 130k exp (give or take), getting from VR1-VR2 requires 450k exp, getting from VR2-VR3 requires 900k exp, going from VR3-VR4 requires 1.3million exp (and it goes up and up).

To explain Veteran Ranks in one meaning would be "New Game+".

Your stats still increase slightly, and you can still get skill points from skyshards and such but at that level it really doesn't make much of a difference. I'd say it's 95% gear based.