power shovel vs backhoe

power shovel and backhoe both are nouns.

Word	Noun	Adjective	Verb	Adverb
power shovel	Yes	No	No	No
backhoe	Yes	No	No	No

As nouns, backhoe is a hyponym of power shovel; that is, backhoe is a word with a more specific, narrower meaning than power shovel:

power shovel: a machine for excavating
backhoe: an excavator whose shovel bucket is attached to a hinged boom and is drawn backward to move earth

Other hyponyms of power shovel include dredge, steam shovel.

power shovel (noun)	backhoe (noun)
a machine for excavating	an excavator whose shovel bucket is attached to a hinged boom and is drawn backward to move earth