All PPS is paying each share an amount that
must include a fee of around 3%
(if the pool uses a lower fee it has a high chance of going bankrupt)
This has zero variance but lower expected reward - the pool covers the mining variance with it's wallet - thus it must have a sizeable wallet.
That's explained here:
https://bitcointalk.org/index.php?topic=104664.msg48795003#msg48795003PPLNS is simply when a block is found, the miners are rewarded for their % of the last N shares on the pool.
i.e. PPL
NS means pay per last
N shares
The N value is up to the pool, but it must be chosen so that miners can't easily game the rewards
(i.e. get more reward per share than everyone else on the pool)
This has variance dependent upon the pool size, but higher expected reward as long as the pool isn't charging a high fee like PPS.
Most PPLNS includes the transaction fees in the reward, but Antpoo doesn't.
... and for those who think variance means a loss, no, it doesn't.
It means up and down i.e. sometimes more and sometimes less.