From my limited understanding of mining, with a pool you are all working together to split the rewards,
with solo mining, you are basically playing the lottery so that you have a very small chance of a large payout?
(And this is a bit of both- CK pool is doing some of the backend work so you dont have to download a whole block chain?)
correct. a pool is normally pooling hashpower to share the rewards; and a solo pool is for people whom can't have the bandwidth or hardware to run a wallet daemon to mine to that (your own pool basically).
I love CK solo because I am on a cellular or a satellite link which has bandwidth and restrictions on data amounts; so not running the wallet at home is mandatory. I make use of every caveat that the solo pool provides because that's the situation i'm in =)
