As Melee I never have to decide if I cancel a cast, I can move when I need to. But I always have to take care about my position (in range + correct positional). I don't have to care if I am in range of the healers because I have to be where the boss is.
I have to manage my uptime for aoe in melee range.

As Range (especially caster) I have to decide when to cancel a cast and when to be greedy and move later. I have to plan when I have to move and my movement needs to be more precise (missile safespot in o7 for example - corrections can not be done during cast). I have to take care of my position, so I don't get out of range for the healers. I have to preplan cone effects because I can not just react to it (melee is easier here).

For me it is just different. But it is not generally easier or harder. And it is extremely dependend on the job you play. SMN is easy to move with some preplanning. BLM is hard to move. RDM is somewhere between (has it's windows where it can move).