I've looked on UESP but i couldn't find a satisfactory answer. Basically, Ragnarok, a 100% vampire High elf born under the apprentice, is about to start oblivion gate crawling for sigil stones. He's looking for any way to increase his survival rate against daedra that will no doubt cast fire. So the question is what's the difference between fire shield, and fire resist? I Picked up the atronach gloves that provide 20 percent fire resist, and made a more powerful fire shield spell at the arcane university but I can't tell what's the difference between the two.

Any other suggestions for increasing my probability of survival in there?

Resist Fire will reduce the damage from Fire attacks. So if you have a 100 point fire ball thrown at you and you have 40 Resist Fire, the fireball will be reduced to 60 points. But if someone hits you a 100 point warhammer then that damage will be not be reduced by Resist Fire

Fire Shield will both reduce the damage from Fire attacks and add to your armor rating. So if you have a 100 point fire ball thrown at you and you have 40 Fire Shield, the fireball will be reduced to 60 points. If someone hits you a 100 point warhammer then that damage will be reduced to 60 points by the Fire Shield.

Resist Fire and Fire Shield are calculated separately. So with 50 points Fire Shield and 50 points Fire Resist, a 100 point fireball will be reduced to 25 points.

The Armor Rating from a Fire Shield will add with other Armor ratings. So if you have 30 points of Armor and then add 10 points of Fire Shield, you will have 40 points of armor. And a 100 point warhammer will be reduced to 60 points.

In short, Fire Shield = Resist Fire + Shield effects combined

It's the same for Frost and Shock Shields, but it changes the first effect with Resist Frost/Resist Shock, obviously.

sounds like the shield effect is strictly better to me then. thanks.

I use the Supreme Magicka mod that alters elemental shield spells, they do not add armor rating, but instead cause elemental damage to melee attackers, which means that Shock Shield is useful when fighting Daedra.

Absolutely. This is how us mages can wear street clothes yet still boast an Armor Class of 75, for that attacking weapon.

The main differences have been kindly mentioned above, but one thing of note is enchanted item loot at higher levels is more in favour of resist over shield.
So look out and keep the 100% resist element rings that pop up frequently when dungeon delving, as they become very handy not so much against spells but magical traps in ruins / oblivion.
Otherwise fire / frost / lightning shield on enchantmants are better, but spell wise its often cheaper magicka wise to cast resist against mages, unless they are combat minded.

Actually, Shield is inferior to the elemental shield effects precisely because it does not include elemental protection and only offers AR boosts. Your AR maxes at 85. You can make clothing with 85 AR only, or you can make clothing with 85 AR PLUS elemental magic protection. I think it's pretty obvious which one is the smarter choice, or at least which choice will help you survive a greater variety of encounters.

Also, Daedra tend to prefer electricity not fire. The Spider Daedra is famous for blasting away with shock spells, for example. Scamps might toss fireballs at you, but they are considerably less powerful than Spider Daedra or other high level Daedra. Oh, and Flame Atronachs, of course... but again, Storm Atronachs are just a wee bit stronger, no?