The only thing OBB and Scary Farm have in common is that both are upcharge Halloween events.
Knott's Scary Farm is an amazing upcharge Halloween event, the oldest at a theme park in the country. The entire park essentially becomes a scarezone, with ample fog machines pumping all night, scareactors everywhere you turn, sliders, and spooky characters with decades of lore roaming around anywhere you are. There are ten haunted mazes, many with incredible set design. Additionally, there is typically great entertainment on offer as well, limited though it sometimes might be.
It's a great event, but it's very much a scary, haunted house-centric event. Not recommended for young kids or anyone who isn't looking for scares.