None of the 2 classes really play alike if you actually group up and get away from leves honestly.

Glad Tanks (strongest tank, worst dmg)
Mar (sorta the middle ground tank and semi decent dmg)
Pug is about evasion tanking and counter attacks
Lancer is one of the most useful classes with a haste ability, evasion down ability, and multiple increase tp gain abilities.
archer is a range dd power house with crazy tp generating abilities (multishot and trifunicate)

Thurm has the strongest dots and debuffs. {easily the best soloing class in the game bar none}
Conj has the main cure spells and strongest nukes.

The only thing that plays the same on them is if you zerg crap down in behest, or you solo (since you are always a dd in that case) or you do leves all the time they are all zergs.

Honestly I feel the classes are what you make of them, I have leveled all classes above 30 now and not 1 of them plays the same at all. Unless you count dmging the mob as being the same.

People need to remember characters are blank canvases. the classes are the paints. You have to make something. Using only 1 color makes a boring painting... which I feel is half the people's complaints with my class is boring. They never made a job out of it.

For those from XI. Make a ranger from your archer, make a pld from your glad, make a blm, make a whm, make a tanking pug, make a dd pug, make a tanking mar, make a dd mar, and the list goes on. Watch any big shell fight a endgame mob and see what they are all doing, you will see then that things are very different in the end.