tea vs oolong

tea and oolong both are nouns.

Word	Noun	Adjective	Verb	Adverb
tea	Yes	No	No	No
oolong	Yes	No	No	No

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

tea: dried leaves of the tea shrub; used to make tea
oolong: Chinese tea leaves that have been partially fermented before being dried

Other hyponyms of tea include tea bag, black tea, green tea.

tea (noun)	oolong (noun)
a beverage made by steeping tea leaves in water	Chinese tea leaves that have been partially fermented before being dried
a light midafternoon meal of tea and sandwiches or cakes
dried leaves of the tea shrub; used to make tea
a tropical evergreen shrub or small tree extensively cultivated in e.g. China and Japan and India; source of tea leaves