For any pool you are using I suggest you do this exercise:
- go Etherscan Ethereum Network Statistics mining calculator: https://etherscan.io/ether-mining-calculator
- insert your average hashrate (same as is being reported by your Pool) and put zeros on power consumption and costs, leave other fields by default
- press Calculate button
- take note your value for "Etherscan Profit per month"
- go to your Pool section of "Estimated earnings" and take note your "Pool Profit per month"
- calculate the difference in % ("Pool Profit per month" - "Etherscan Profit per month") / ("Etherscan Profit per month")
- you will notice that there is a negative difference between -15% to -20%
What can this explain big difference
Why your Pool is expecting to reward you less 15% than is expected by the Ethereum Network Statistics?