PIP-18 use balances of PEG for each address which is more complicated. It is the balance of PEG for the address (assuming it has not be delegated)
It quits looking at the rich list, and just consider the top 100 submissions with the highest stake
PIP-18 pays out with the ratio of the total PEG staked. (Removes old top 100 PEG addresses staking reward and give staking opportunity to all PEG holders)