My understanding of the difference is thus:

Dealing: As long you do not role an X and you roll sufficient range for a ranged attack, this is the total number of hearts you produce through surges, abilities, overlord cards etc. Defence shields rolled by the defender do not effect this number.

Suffering: This is the total number of hearts the defender places on his hero sheet immediately after the attack is resolved. Defence dice rolled by the defender do effect this number as well as any other defensive abilites, overlord cards or equipment abilities that trigger during an attack. Jain's hero ability does not affect this number.

Does that sound about right? I was reading through potential quests to do nxt and came across this paragraph on page 16 of the Lair of the Wyrm quest guide/rulebook under Covering The Trail for the At The Forge quest.

"When attacked, a Trail token rolls 1 grey defence die, which is rolled by the last hero that activated. If the attack deals at least 1 [heart] to the Trail, the overlord removes the Trail from the map and it back in his supply."

If my understanding is correct, isn't the grey defence die completely unnecessary? As long as you don't roll an X and have range, your gauranteed to deal at least 1 heart right? Reading that paragraph has caused me to question if I've got it right so I figured I'd post a question about it.

Nope. "Damage Dealt" is all hearts, including those added from surges and other abilities MINUS all shields, including those added from other abilites.

Think of conditions- dealing at least 1 damage means AT LEAST 1 heart isn't cancelled by a shield.

A figure must suffer damage equal to the damage dealt unless it has abilities that change that (like Jain Fairwood.)

ahh okay. Thanks for the clarification. For some reason I remember conditions saying you must deal 1 heart after defence dice have been rolled to apply which I took as a sort of caveat to my definition of dealing damage. And Jain's hero ability does reduce damage suffered? So I had it completely wrong? Awesome. At least my Airborne card just became alot more useful...

Well- she can suffer damage as fatigue instead.

ahh okay. Thanks for the clarification. For some reason I remember conditions saying you must deal 1 heart after defence dice have been rolled to apply which I took as a sort of caveat to my definition of dealing damage.

Yeah, FFG are known for writing redundant clarifications like this on some cards and not on others. It's a big contributor to the amount of confusion we run into while playing.

Damage dealt and damage suffered are the same thing. Damage suffered generally means Wounds are lost, but there may be some abilities that convert it to Fatigue, as mentioned. And, of course, suffering Fatigue will convert to Wounds if the victim has no Fatigue left to lose.

Occasionally there may be effects that talk about "Damage rolled," which would be prior to subtracting defence dice or other reduction abilities, though. The difference does exist, but it's not between "dealt" and "suffered."