No, Guild Wars doesn't do versions, they did what they called 'campaigns' which are basically stand alone games that can be crossplayed with each other. In fact each one is pretty much cross-seeded with each other. Each one has 'theme' to it with the character looks reflecting that theme.
The 'original' campaign/game was
Guild Wars although the players nicknamed it 'Prophecies' so you'll hear it called that or 'Proph.' That game took place in Tyria with the 'core' professions of Warrior, Elementalist, Necromancer, Monk and Ranger. It has a very European country side feel to it.
Then came
Guild Wars Factions, which takes place on the continent of Cantha, and during which you chose sides or which 'Faction' you'll play for

In addiciton to the core professions it introduces two new and exclusive professions to that game; Assassins and Ritualists. It has a very Asian feel to it. It does have references to NPC's from Prophecies in it. This is by far the easiest and fastest one to get through, many people use it to quickly level characters.
The last campaign to be put out was
Guild Wars Night Fall, it takes place in Elona and introduces in addition to the Core professions, two new and, exclusive to the game, classes Paragon and Dervish. It has a very Northeastern African feel to it.

Heroes are also introduced in this campaign, which allows you to have your own personal set of personalized of, for lack of a better term, near NPC henchmen. However you can control their skills if you'd like
Most recently ANet released an extension/expansion pack titled:
Guild Wars: Eye of the North You'll see this referenced as 'GWEN' or 'EOTN' Which actually expanses on the original map of Tyria, but can be used as an expansion for any of the campaigns.
Incidentally if you play this weekend there is an event for Factions you'll run into. The Canthan New Year is this weekend
WarBlade could probably add more :/ that's just the most basic I can boil it down to without being sidetracked into Elite Missions, Factions, Heroes, dungeons etc..etc..
