An actuator is a device which strokes a valve or other device in accordance with the control signal transmitted to the transducer on the actuator. The transducer usually converts the control signal to a proportional air signal which operates the actuator using a large diaphragm opposing a spring.
A transducer is a device which converts on engineering variable to another engineering variable. Such as an I/P (current to air pressure) transducer. The engineering units can be many types.
Electrical usually indicates a device using many watts such as a motor. Electronics usually indicates precision low current devices such as television, electrocardiogram machines, etc.