im afraid every class will eventually be the same, and there's no defined role for each class like there was in XI.
This is one of the few game parts where 14 is clearly superior to 11, and you miss it?
Why would every class be the same? There are abilities which need the tool/weapon for that class in the main hand. Also the abilities can only be incorporated from classes you've leveled high enough. Seeing as you need quite a bit of patience after 20, I'm not afraid of that happening. Also there's a limit of 30 (29 or 28 if you discount your standard attacks) abilities you can put into your action bar. Even further there's a limit on how many abilities you're allowed to use simultaneously determined by the rank of your current class.
This may sound all very intimidating, but actually it's quite flexible and allows more combinations than were ever possible in FFXI. That you can even use abilities from three different classes in one fight makes this more potent than the subjob system of FFXI.
And thank the twelve that there's no defined role. Gone are the days where a class is pigeonholed. That's a boon, not a bane.