The difference lies in the fact that its closing part is valve body, which revolves around the center line to achieving the opening and closing effects.
Farqiga u dhexeeya ayaa ah in qeybta xirmidda waalka kubbadu uu yahay kubad, taas oo ku wareegeysa hareeraha khadka dhexe ee jirka waalka si loo gaaro furitaanka iyo xiritaanka.