axle vs driving axle

axle and driving axle both are nouns.

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

As nouns, driving axle is a hyponym of axle; that is, driving axle is a word with a more specific, narrower meaning than axle:

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

Other hyponyms of axle include dead axle, journal, live axle, trailing axle, blind axle.

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