Some people say "Rocket Engines" and some people say "Rocket Motors"
.. what's the difference?
Motor: A Motor is a device that produces motion.
Engine: An Engine is a device that produces motion through the use of a combination of moving parts
An engine is a motor, but a motor is not necessarily an engine
When this Theory is applied to Rocketry:
Solid propellant rocket motors of the type used in model & high power rocketry have no moving parts and are therefore Motors.
But then why do some manufacturers stamp "Model Rocket Engine" on their motors?
Well "engine" sounds more sophisticated and powerful than "motor", doesn't it?
Most manufacturers of Model Rocket Motors, still stamp their Motors as "Model Rocket Engines",
but they're also stamped as "Model Rocket Motors" in really small letters.