Alliances in ESO are the equivilant of factions in TSW.
The difference seems to be that in TSW any faction can PvE play with each other, they can not be in the same guild.
In ESO, any alliance can be in the same guild, but CAN NOT PvE play with each other. (Maybe that was a feature disabled in betas, maybe it will change.) But for now it seems the smartest thing to do is agree on the same alliance if we want to do questing and dungeons together.
In ESO
ALL your characters, whatever their 'home' Alliance, are tied to the alliance of the GUILD LEADER..!!
Each alliance has it's own PvE areas, with no crossover!!
If you & your friend(s) choose a different Alliance to you, next time u see them will be in Cyrodill or @lvl 50....
atm the whole 'end-game' is built around the 3 Alliance war in Cyrodill
There are campaigns, which last 3months + some smaller stuff i'm not sure about.
Campaigns are limited to 2000 ppl at a time.
In ESO you will have a starting shard just like TSW & you will be tied to pvp on said shard...
There is a US super server & an EU super server....
I doubt US & EU players will end up in the same pvp campaign....
I also doubt that we can all agree to the same faction...
I would suggest trying to see if we can have a guild per faction as we do in TSW...
PLUS a 'globo' guild so that we can all see main guild chat (u can join 5 guilds *shrugs*)
In SW:TOR you could register guilds & members in advance, so you all ended up in the same world,
Not in ESO tho... :/
The whole thing seems stacked against existing organised guilds ending up together, not sure if this is by accident or design.......
But think if 30-50 of us were all running together in a single 2000man campaign....!
I'm pretty sure we would quickly dominate the opposition (i'm crap at pvp btw...)
Not quite sure how this will pan out really....