Power-assisted steering and Steering system

Power-assisted steering noun - Automotive steering where engineer power amplifies the torque applied to the steering wheel.

Steering system and power-assisted steering are semantically related. In some cases you can use "Steering system" instead a noun phrase "Power-assisted steering".

Steering system noun - A mechanism by which something is steered (especially a motor vehicle).

Power-assisted steering and steering system are semantically related. Sometimes you can replace phrase "Power-assisted steering" with "Steering system", this phrases are similar.