tea leaf vs green tea

tea leaf and green tea both are nouns.

Word	Noun	Adjective	Verb	Adverb
tea leaf	Yes	No	No	No
green tea	Yes	No	No	No

As nouns, green tea is a hyponym of tea leaf; that is, green tea is a word with a more specific, narrower meaning than tea leaf:

Other hyponyms of tea leaf include tea bag, black tea, oolong.

tea leaf (noun)	green tea (noun)
dried leaves of the tea shrub; used to make tea	tea leaves that have been steamed and dried without fermenting