Yea if you're going back from VII or VI where the stories are miles ahead of this game, it's hard. But FF1 and FF3 really did had blank slates. This is the first time you started to get real story and the characters weren't clones of one another, and this I think influenced FF4. If you mean gameplaywise, yes you can have anyone do anything, but that's not unique to this installment. Their initial stats are different, with Maria having the most intelligence so you probably want her to be a mage, and Guy has the most strength so make him a swordsman, and that leaves Firion(iel) as your healer. But you can switch it up if you want.