HS11 are different at the handlebar end - they have a resin (read plastic) housing - in most cases the lever is metal - but it can be resin as well i think. You get a little extra flex at the lever with the HS11 as the resin flexes- but its only a little. If they are fitted on a bike already, its ok - the function is still better than V brakes or crap discs - and you can upgrade quite easily with a new cylinder, and the better lever shape of the HS33. If you are buying them as parts though - its not much extra for the HS33, i'd stretch to those every time.