A shunt resistor is used to change the range of a meter reading. For instance, a current meter that normally reads from 0 to 1ma, can be made to read from 0 to 1amp by the addition of a shunt across it's terminals. There might be other applications of a shunt that I don't know about, but bottom line, it is placed across an existing path to lower it's resistance.
A sense resistor is used to "sense" the current in a line for the purpose of reading that current -- usually in a feedback loop. That can be to determine it's magnitude or to respond to a certain level.
There is a subtle difference: a "shunt" _shunts out_ an existing path, whereas a sense resistor is not placed across something, but exists as a distinct path.
