self-starter vs human dynamo

self-starter and human dynamo both are nouns.

Word	Noun	Adjective	Verb	Adverb
self-starter	Yes	No	No	No
human dynamo	Yes	No	No	No

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

Other hypernyms of self-starter include ball of fire, fireball, powerhouse.

self-starter (noun)	human dynamo (noun)
an electric starting motor that automatically starts an internal-combustion engine	a highly energetic and indefatigable person
an energetic person with unusual initiative