When I compare the number listed under "the last 24hr's profit" to the most recent payout why don't the number's match?
Because you are paid in BTC and we mine different coins which need to be exchanged into BTC first. Last 24h profits is your share of what the pool mined in these 24 hours. Payouts are sending you already exchanged BTC. Coins mined in day X are paid mostly in days X+1 and X+2 and them some much lower amounts in later days depending on how quick is the coin to mature and exchange.
So basically it is the difference in the fluctuation of the prices of the coins from the time they are mined until the time they mature and are payed out that causes the difference in numbers?
No, it's not this (this affects the numbers as well, but only slightly)
Here's a very simple example:
Let's say we mined only two blocks in the day and your share is 1.00 XXX which is worth 0.1 BTC and 1.00 YYY which is worth 0.05 BTC (XXX and YYY are some coin symbols). So your profit for the day was 0.15 BTC.
XXX was mined early in the day so it was exchanged in the same day to 0.1 BTC. But YYY was mined at 8pm. It takes 3 hours to mature on average so it's 11pm when it's matured and we can send it to exchanges. It's midnight when it arrives at exchange. It's auto exchanged couple of minutes later. Then it's withdrawn from exchanges couple of hours later and finally arrives back at the pool at 4am in the morning.
In the meantime there's a payout at 1:30am in the morning. At this moment you have 0.1 BTC exchanged (coming from 1 XXX) and you have 1 YYY still unexchanged, which is worth 0.05 BTC estimated. So you are paid 0.1 BTC because the other 0.05 BTC is still not exchanged into BTC.
You're paid the remaining 0.05 BTC one day after when the next payouts run.
So your profits for day X were 0.15 BTC, of which 0.1 BTC was paid in day X+1 just after midnight and 0.05 BTC was paid in day X+2.
If you were mining in day X+1 as well, then payout on X+2 will also contain most of your profits from X+1 (and the remaining of profits from X).
I hope it helps.