fifth wheel vs redundance

fifth wheel and redundance both are nouns.

Word	Noun	Adjective	Verb	Adverb
fifth wheel	Yes	No	No	No
redundance	Yes	No	No	No

As nouns, redundance is a hypernym of fifth wheel; that is, redundance is a word with a broader meaning than fifth wheel:

Other hypernyms of fifth wheel include redundancy.

fifth wheel (noun)	redundance (noun)
a steering bearing that enables the front axle of a horse-drawn wagon to rotate	the attribute of being superfluous and unneeded
an extra car wheel and tire for a four-wheel vehicle
someone or something that is unwanted and unneeded