Contactors, Starters, Overload Relays
A motor starter is a contactor plus an overload relay; without an overload it is just a contactor.
A motor starter starts and stops a connected motor load and will provide protection in case of a sudden loss of power or if the motor overloads. A contactor is similar to a relay (but can handle larger amounts of electrical power and handle higher voltage loads) and is used for switching current on and off in a circuit. Contactors are used to control electrical loads and motors without providing overload protection.
a.k.a. motor starter, IEC contactor, dp contactor, thermal overload relay, motor protectors