Yes, if i understand correctly, Lets say the block needs X zeros to be solved and you be rewarded, for simplicity sake lets call this difficulty to solve a block is 100, so if your share has a difficult of 100 or bigger then you solve the block, your share having bigger than 100 difficulty also solves the block but you get no extra benefit. If you mine a share at 10 difficulty or 50 difficult it also does nothing as it doesnt solve a block, however since a pool is trying to pay for work done so luck (but you dont care about this). So lets say a pool set your difficulty to 10, this means shares with difficulty of 10 are counted as 1 share (worth 10 points), even if you manage to get a 100 or even 1000 difficulty share the pool will not give you more than 10 points. If your difficulty set by pool is 20 then shares mined under that will be deleted and every time you have a share with a difficulty bigger than 20 you get credit for 20 points exactly. Understood?
The pool measures your hashrate by the number of your submitted valid shares that has difficulty greater than your worker diff multiplied by your worker diff.
Your Work = (Number of your valid shares) * (Worker diff)
It does not matter at all how much is your found share's diff above your worker diff regarding your payment.
So if you have worker diff at 10, nobody cares if your share diff is 15 or 50. It only count as one share.
Of course if it's above the network diff then you solved a block, but you won't get a bonus for that from the pool, because the reward is split according to only the (number of your shares) * (worker diff).
Ksin:
The exact answer for your question is that difficulty is measured in hashes.
In your example 17.799G diff means that finding a share with that many leading zeros takes 17.799 x 10^12 hashes in average.
https://ethereum.stackexchange.com/questions/29784/what-is-the-unit-for-measuring-difficulty
Thanks for making my explanation more clear, i hate words
