Jester David
Hero
Right. Either things are open or closed. All-or-nothing.The OGL is not an all-or-nothing license. You, as the participant, get to declare which parts of a book are Open.
There's six different flavours of Creative Commons with different levels of sharing (remixing or not, commercial or not, and combos).The CC is an all-or-nothing license in and so far as the participant is declaring the entire book to be public domain.
It doesn't have the same delineation of open & closed in a single book as the OGL but you can allow more fan use (non-commercial) or expansion without revision. I imagine you could have different CC licences for different chapters of a book as needed. But, if you're going OGL/CC you likely want to make your game open and sharable, so this is less an issue.
Other than being able to declare certain sections of a book closed, there's less advantage to the OGL for non-d20 systems. If you're making a d20 game, access to the SRD is invaluable and you'd be foolish not to go OGL. Heck, the OGL might be the way to go for a semi-generic fantasy system, as you easily gain access to common monsters and classes.
Otherwise, the CC gives you more flexibility. And it's just more accessible for non-lawyers and casual creators. There's less active help for the OGL currently.