The expensive badgers are unionized. Also: better hair quality (softer), better quality (less hairloss, hopefully), natural tips not machine-clipped, denser knot. And often a much nicer handle. Principally, you can lather up with the cheap one just like with the more expensive one, but the more expensive one might feel and look a lot nicer.
i did notice a few hairs on my bowl... ill have to look into a more high quality brush for when this one gets worn out.