difference gate

Noun

 * 1)  a logic gate whose output is TRUE when the two inputs are different; a Boolean logic XOR gate.

Usage notes
A difference gate, when the term is used to mean the XOR function, is not the same function as difference in set operations. The former is $$\scriptstyle A \overline B + \overline A B$$ while the latter is $$\scriptstyle A \overline B$$