text: Though the terms equivalence point and endpoint are often used interchangeably, they are different terms.  Equivalence point is the theoretical completion of the reaction: the volume of added titrant at which the number of moles of titrant is equal to the number of moles of analyte, or some multiple thereof (as in polyprotic acids).  Endpoint is what is actually measured, a physical change in the solution as determined by an indicator or an instrument mentioned above.
  There is a slight difference between the endpoint and the equivalence point of the titration. This error is referred to as an indicator error, and it is indeterminate.