excavator vs power shovel

excavator and power shovel both are nouns.

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

As nouns, excavator and power shovel are synonyms defined as:

Other synonyms of excavator include digger, shovel.

excavator (noun)	power shovel (noun)
a machine for excavating	a machine for excavating
a workman who excavates for foundations of buildings or for quarrying