I have played RDM until level 47, and now I've started playing WAR and have it at level 20. To me, the two jobs are very similar.
The RDM is the jack-of-all trades. At the start, this includes melee, but it starts to diminish and he becomes the flexible "fill-in-the-gaps" caster in the back. Yeah, you can still melee, but your real strength is your casting.
The WAR seems like the RDM of the front lines. You start off being one of the best tanks and a solid damage dealer. As you get PLD's and DRK's, you are no longer the best of either, but you are still able to fill both roles. You can use your subjob to adjust this a little (ex: sub PLD or MNK to be a better tank, DRK or THF to do more damage) the same way that an RDM will sub different mage classes to shift their focus. Also, the WAR is able to use more weapons than any other class. As long as you have several weapon skills leveled to acceptable levels, and have some decent wepaons on you, you are guaranteed to be able to fill in the gaps in any skillchains that the team is trying to do. You become the "Red Warrior", filling in the gaps in the front lines like the "Red Mage" fills in the gaps in the back.