which has better survivability and faster leveling?

I would argue druids are better in many if not most areas when leveling up.

Some differences:

Druids:

Much less downtime while leveling up. You almost never have to eat or drink or bandage.

Less gear dependent leveling up.

Much harder to kill (allowing you to survive against multiple mobs, and even kill elite mobs or mobs many levels higher than you).

You can escape from bad pulls and avoid death (and corpse runs). If warriors get adds or have bad pulls they die.

Have a fast travel form at level 30.

Can stealth (turn invisible) which allows you to complete lots of quests that your warrior would need to kill many mobs to finish.

Your tanking Spec is your dps Spec. For warrior's it's either/or.

However

Druids are expensive to buy skills for because your buying skills for healing, tanking, dps'ing, and even nuking.

Druids are complicated and require attention and thought to play. Warriors are relatively simple by comparison.

At level 70 you will carry around 2-3 backpacks full of gear to use in different forms. A DPS set, a Heal set, and a Tank set. Some will even add a Caster set, and a PvP set. Farming all this gear takes time.

If you don't like tanking or healing, you may be disappointed at level 70. Druids are generally frowned upon as a DPS class, whether Moonkin or Cat. There are exceptions to this, but in general it is true.