subscriber vs booster

subscriber and booster both are nouns.

Word	Noun	Adjective	Verb	Adverb
subscriber	Yes	No	No	No
booster	Yes	No	No	No

As nouns, booster is a hypernym of subscriber; that is, booster is a word with a broader meaning than subscriber:

Other hypernyms of subscriber include admirer, champion, friend, protagonist, supporter.

subscriber (noun)	booster (noun)
someone who contributes (or promises to contribute) a sum of money	an additional dose that makes sure the first dose was effective
someone who contracts to receive and pay for a service or a certain number of issues of a publication	the first stage of a multistage rocket
someone who expresses strong approval	an amplifier for restoring the strength of a transmitted signal
	a thief who steals goods that are in a store
	someone who is an active supporter and advocate
	a person who backs a politician or a team etc.