driving axle vs axle

driving axle and axle both are nouns.

Word	Noun	Adjective	Verb	Adverb
driving axle	Yes	No	No	No
axle	Yes	No	No	No

As nouns, axle is a hypernym of driving axle; that is, axle is a word with a broader meaning than driving axle:

driving axle: the axle of a self-propelled vehicle that provides the driving power
axle: a shaft on which a wheel rotates

driving axle (noun)	axle (noun)
the axle of a self-propelled vehicle that provides the driving power	a shaft on which a wheel rotates