What is the difference between a prayer being invalid and it being void?

There is no difference between nullity (butlan) and invalidity (fasad) in prayer according to the majority of scholars and the relied-upon view of the Hanafis. Both terms signify that the act of worship does not produce its intended effect, or that the obligation to make up the prayer is not lifted, or that the act does not conform to the divine command. The Malikis, Shafi'is, and Hanbalis hold that there is no distinction between the two in transactions generally, whereas the Hanafis differentiate between them in transactions, but they concur with the majority regarding their interchangeability in acts of worship.