rudder vs steering system

rudder and steering system both are nouns.

Word	Noun	Adjective	Verb	Adverb
rudder	Yes	No	No	No
steering system	Yes	No	No	No

As nouns, steering system is a hypernym of rudder; that is, steering system is a word with a broader meaning than rudder:

rudder: (nautical) steering mechanism consisting of a hinged vertical plate mounted at the stern of a vessel
steering system: a mechanism by which something is steered (especially a motor vehicle)

Other hypernyms of rudder include steering mechanism.

rudder (noun)	steering system (noun)
(nautical) steering mechanism consisting of a hinged vertical plate mounted at the stern of a vessel	a mechanism by which something is steered (especially a motor vehicle)
a hinged vertical airfoil mounted at the tail of an aircraft and used to make horizontal course changes