human dynamo vs doer

human dynamo and doer both are nouns.

Word	Noun	Adjective	Verb	Adverb
human dynamo	Yes	No	No	No
doer	Yes	No	No	No

As nouns, doer is a hypernym of human dynamo; that is, doer is a word with a broader meaning than human dynamo:

Other hypernyms of human dynamo include actor, worker.

human dynamo (noun)	doer (noun)
a highly energetic and indefatigable person	a person who acts and gets things done