I played FFXI from release until EQ2 release, and still play now and then. These are the things that I think are kind of alike.
Groups-Six is the max number in a group (like ffxi), but you can be very effective with less.
Raids-Same thing as an alliance in FFXI.
HO's-Same thing as a skillchain(renkai)in FFXI, but easier and not only do more damage, but give buffs as well. I am sure there is alot more but someone else can mention them.
I like EQ2 much better than FFXI. The game is just more fun to me. Some of the big things I like better are, if I log in for just an hour I can still do something. I can solo....for xp! Characters and armor are much more unique. You can decorate your house and people can come over and see it. A guild (linkshell in ffxi) does mean something. It affects your status with the city, and you can do quests to level your guild.
Anyway there are alot of reasons I like this game. I beta tested WoW for a while, and it wasn't for me. I am not to big on the PVP, and I do like to group more than play solo. So far the only thing that sucked for me in EQ2 was getting groups for the armor quests because I have limited play time.
Good luck in what ever game you choose!