rocket fuel vs explosive charge

rocket fuel and explosive charge both are nouns.

Word	Noun	Adjective	Verb	Adverb
rocket fuel	Yes	No	No	No
explosive charge	Yes	No	No	No

As nouns, explosive charge is a hypernym of rocket fuel; that is, explosive charge is a word with a broader meaning than rocket fuel:

Other hypernyms of rocket fuel include burster, bursting charge, charge, propellant, propellent.

rocket fuel (noun)	explosive charge (noun)
an explosive charge that propels a rocket	a quantity of explosive to be set off at one time