power-assisted steering vs power steering

power-assisted steering and power steering both are nouns.

Word	Noun	Adjective	Verb	Adverb
power-assisted steering	Yes	No	No	No
power steering	Yes	No	No	No

As nouns, power-assisted steering and power steering are synonyms defined as:

power-assisted steering and power steering: automotive steering where engineer power amplifies the torque applied to the steering wheel

power-assisted steering (noun)	power steering (noun)
automotive steering where engineer power amplifies the torque applied to the steering wheel	automotive steering where engineer power amplifies the torque applied to the steering wheel