megaton vs explosive unit

megaton and explosive unit both are nouns.

Word	Noun	Adjective	Verb	Adverb
megaton	Yes	No	No	No
explosive unit	Yes	No	No	No

As nouns, explosive unit is a hypernym of megaton; that is, explosive unit is a word with a broader meaning than megaton:

megaton: a measure of explosive power (of an atomic weapon) equal to that of one million tons of TNT
explosive unit: any unit for measuring the force of explosions

megaton (noun)	explosive unit (noun)
one million tons	any unit for measuring the force of explosions
a measure of explosive power (of an atomic weapon) equal to that of one million tons of TNT