Khiyar al-aib is an option (khiyar) to annul a transaction for defects in the subject matter (whether the object of sale or the price or thaman). On the other hand, khiyar al-tadlees is an option (khiyar) to rescind a transaction for fraudulent concealment of defects.

In the case of khiyar al-aib, there is in principle no intentional concealment of defects. That is, neither party has hidden, or is believed to have hidden, any defects associated with his respective subject-matter (countervalue/ badal). While, in the case of khiyar al-tadlees, a contracting party is found out to have presented misleading description or details about the subject-matter to the other party (or likewise, to have intentionally concealed unfavorable shortcomings in the subject-matter).

In both cases, a contracting party has the right to rescind the transaction or to consummate it. However, consummation in the presence of aib or uyub (defects a party was unaware of their existence in his respective subject matter-at the time of contracting) would entitle the injured party to some rebate (known in shari’a parlance as arsh). This rebate would be estimated based on the difference between the value of an intact object of sale and a defected one, everything else being equal.