Software defect is nothing but an error created by a programmer while development. Fault is when your software is error free, yet it couldn't function properly. 

These things are very similar and sometime creates confusion. Here is what i think about those...

Fault: a condition that causes the software to fail to perform its required function. 

Defect: when actual result does not match with specification

Change-proneness may be used in evaluate software quality. I am not sure about it. Lets wait for the experts.

Error: “A difference…between a computed result and the correct result”

Fault: “An incorrect step, process, or data definition in a computer program”

Failure: “The [incorrect] result of a fault”

Mistake: “A human action that produces an incorrect result”

change-proneness: The extent of change of a class across the versions of the system.