Think of a warden as a defensive druid and a fury as an offensive druid.
This is not to say that a fury can't heal or that a warden can't nuke... only that each class leans a little more in one direction or the other...
I play both and can honestly say that while both solo well and that although either one does just fine in group or raid situations, I prefer my warden.
Wardens get fewer nukes and dots but a wider selection of heals. They also get evac. Furys get a better selection of nukes and dots and fewer heals but do have a nice selection of buffs and a group invis. Reuse timers are a little different with wardens getting to use their nukes more often. (good thing since we only get a couple!)
Both get roots, rezzes and the ability to port their group to any of the 5 druid rings. In addition, they each get a host of other in interesting unique spells.
For example, furys get a spell that heals the whole group when the mob dies and an interesting AoE Dot. Wardens get a dumbfire pet that is a pack of attack dogs and a healing tree.
Both wear leather armor and can use 1 or 2 handed blunt weapons (hammers, flails, wands & staffs), and also some one handed bladed weapons.
IMHO, you can't make a wrong choice if you pick a druid! I think that between the two, they are the best healers in the game! (but maybe I'm biased!)