Both have the same eHP.

Inner Beast is to make up for the lack of blocking.

Warrior's damage is higher while tanking than PLD, but it's not by a huge margin or anything.

PLD has access to Hallowed Ground, a cooldown that makes you immune to most damage (read: anything that isn't designed to one shot you regardless) for 10s.

Neither is superior, in 8 man content you want both. In 4 man content it doesn't matter which you choose as they can both get the job done. Who Main Tanks and who Off Tanks depends on the fight.