Simple.
PANSOPS: Maintain runway track. (i.e drift corrected).
TERPS: Maintain runway heading. (i.e no drift correction).
TERPS are used in N and S America, Japan, Taiwan and Korea. Rest of the world uses PANSOPS. Know what you should be using (it should tell you what rules you should be following on your approach plates). If you are flying one of the more modern glass Boeings, the FMC knows where you are and applies the correct command to the FD/AP.