This forum is the "original" cocos2d forum, while http://forum.cocos2d-spritebuilder.org actually is the old sprite builder forum. When Apportable stopped sponsoring, they renamed it, added a cocos2d logo, merged some of the cocos2d posts, and redirected cocos2d-swift to point to it.
I then redirected cocos2d-iphone to this forum, and that is the reason there are two fora today.
@slembcke was made admin of the sprite builder forum when everybody else left, but he doesn't seem to visit it anymore, and hasn't posted anything for months.
I have asked both him and Collin if it would be possible to somehow merge the fora, as this clearly would be in the best interest of the remaining users. It seemed to be okay with Collin, but @slembcke has never answered any of the requests. Maybe he has moved on, and is too busy. I do not know.