Reported Hashrate is utilized by ethminer, a piece of mining software. It submits the hashrate of your actual hardware (what you see in your console) to the pool. This allows you to compare it to your calculated hashrate.
Reported Hashrate is just a convenience item and not required to mine on the Ethereum pool. However, it does allow you to compare your submitted hashrate to your calculated hashrate which can be useful to you.
Reported Hashrate does not affect payout.
Calculated Hashrate takes the amount of valid shares your miner has submitted over a period of time and uses a formula to convert this into a readable hashrate. This number can fluctuate, sometimes being lower or higher than your actual miner's output hashrate in the console.
Calculated Hashrate does affect your payout.
Below is a chart comparing Reported Hashrate vs Calculated Hashrate.
As you can see in this case the Calculcated Hashrate is actually higher then the Reported Hashrate resulting in a better payout then expected.