The primary differences between a Jua’alah and an Ijarah are below:

  1. The specified payment in Jua’alah cannot be paid until the task is completed, whereas interim payments are accepted in an Ijarah arrangement. In a Jua’alah contract, payments in advance or interim payments are not legal.
  2. Jua’alah has some gharar in it, which is approved by the Shari’ah, whereas an Ijarah contract has no gharar.
  3. The Jua’alah contract is a permissible contract, which means it can be invalidated by either of the parties at any time, whereas an Ijarah contract is an obligatory contract which cannot be invalidated after being signed.
  4. An Ijarah contract has a specified time-frame attached to it, whereas a Jua’alah contract has no time-frame (though a minority opinion among the Malikies argues that a time-frame is necessary).
  5. The Jua’alah cannot be increased or decreased once the task has started.

Source: Abdelhaleem, 6.