power shovel vs excavator

power shovel and excavator both are nouns.

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

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

Other synonyms of power shovel include digger, shovel.

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