Oh, and another thing raycasting does.
When Raycasting and Collision are turned on, you can 'step' ontop of a brick higher than the one you currently stand on. (as long as it's not too high)
When Raycasting is off, and collision is on, you can no longer 'step' ontop of the brick, unless it ofcourse is equal height. (Lower would be falling onto, not stepping, anything higher cannot be step onto)