Both WAR and DRK have extremely similar play styles in raid-- a 10 second burst window on 90 second cooldown, and the rest of the downtime is pretty uneventful. However, DRK is a heck of a lot busier during those big windows, while WAR is very low-apm. The only difference is DRK is a lot tankier to tank busters while WAR does better sustain due to self heals.

in dungeons, again, both are similar except that DRK keeps alive by spamming TBN whenever possible, while WAR has to put in a little more thought with their nascent flash and timing it with chaotic cyclone and decimate to get the most out of their healing.

You'll hear often that GNB DPS is the best, but really, all the tanks have very similar DPS. It's like calling GNB the tallest toddler.