Well there are a few things that seperate them, but how hugely different they are from another MMO is dependant upon the person because some view differences differently XD;
-Cutscenes: In FFXI, certain Missions(quests that drive storyline) and Quests(Side-quest) have cutscenes. So far this is revolutionary and is not in any other MMO to date as of this time.
-Job Change: Sure you cant change your race, but you can easily change your job in your Mog House. Many MMOs require you to make another character or reset your level of your current class, not the case in FFXI.
-Driving Story: Currently, the game offer Missions that pursue the storyline in FFXI. There is 3 different storylines following the 3 nations(especially after the rank 6 battle that explore the nations and lore more), Zilart missions (Expansion #1), and the COP or Chains of Promathia Missions(Expansion #2). No other MMO to my knowledge really follows story as close as this MMO. However some people feel the story is weak because it may be long drawn out(ie: need job lvled up or not ready for it yet). Cutscenes are very good, characters are memorable and have taste(even most npcs), and if you arent spoiled, some things can stun you. Unlike most MMOs, PvP is not the main focus or staying power for this game, a large portion is story and time with your LS(guild) friends.
-Team play: Yes you can party in other games, but in this game partying is everything. Only the Beastmaster job can solo all through the game(and i think its limited now with a recent patch), everyone else must party. If you dont like partying or have the time to do it, this game might not be for you. The things you do solo are quite limited compared to the things you need to do partying. If you are a lone wolf, stay away...NOW.
-Timesink: This isnt as new, however unlike WoW you need alot of time, patience, and gil to go forward in the game. You can fail a boss fight over 5 times and be extremely frustrated. However that means that every single achievement you get, is worth that much more. Like failing 5 times, then finally triumphantly beat it with your friends, is much more rewarding. However if you like more cheap instant gratification, you wont find much in FFXI. And no you cant expect to gain money by exping, you have to work for your money.
-Community: Yes theres always gonna be assholes, but so far i feel theres ALOT less assholes in this game than others. The higher level you go, the more the community seems apparent.
-N00bFriendly?: Yes, most people are very willing to help out a new player through the ropes, and give a few handouts to help you on your feet. Any questions and the LS will usually very readily help you out. At least on mine i feel. Theres always new jobs that needs to be leveled. And if you have a Gold World Pass and register it you can get level capped cap to wear, that you can party with your friend that invited you for all his jobs under 50. However the game itself doesnt show its true potential until you level up more and have good connections.
-Innovative Battle System: The actual hack&slash isnt innovative, however skillchains and magic bursts are and promote cooperation between party members.
Skillchain: You have a weapon that can use a special move(sorta like a limit move) everytime it reachs 100%TP by hitting the mob or getting hit. You coordinate with another melee and if you use the special weapon skill in the right order with the right timing along with the correct skill, you can create a Skillchain that has an elemental effect that does alot more damage than what you would without it. Magic Bursts allow any magic element that fits the skillchain to do more damage than usual making it extremely strong vs the monster. Less apparent in lower levels, but highly recommended if not required to do in higher levels where it can cleanly kill an enemy in under 15 seconds if done correctly and fast enough.
Crafting: Anyone can do it, its not limited to certain classes like some other MMOs i played. Interactive fishing is fun too ^^
Crossplatform: We play with PS2, PC, and Xbox360(future) players on same server. Also play with Japanese players as well who use same servers. We communicate with a built in auto-translate function or we can use romaji.
and lastly, Mandragoras are the best! <3 Pa!
My Youtube Page - Full of Capcom vs SNK 2 goodness!
Check it out Nya~! @.@
貓..貓..Yeh! X3