attributes set within init

I've watched this video (and the next one) several times and several things are unclear to me. First, what is the difference between an attribute set this way:

class Thief: sneaky = True

and the same attribute (sneakiness) set within the init, like this:

def __init__(self, name sneaky= True, **kwargs):

?? And while I'm asking questions-- in the next video Kenneth types "pass" beneath the subclass's init: what does "pass" mean? Is the subclass's init a separate thing from the superclass's init? Is the new init (the subclass's init) the thing that overrides the original init (the superclass's init)? Meaning you would ONLY need super() with an over-riding init? Finally (for now): why does Kenneth say the ability to set sneakiness has been lost, when the class still states sneaky = True?

Thanks!