tupelo vs water gum

tupelo and water gum both are nouns.

Word	Noun	Adjective	Verb	Adverb
tupelo	Yes	No	No	No
water gum	Yes	No	No	No

As nouns, water gum is a hyponym of tupelo; that is, water gum is a word with a more specific, narrower meaning than tupelo:

tupelo: any of several gum trees of swampy areas of North America
water gum: columnar swamp tree of southeastern to midwestern North America yielding pale soft easily worked wood

Other hyponyms of tupelo include Nyssa aquatica, black gum, Nyssa sylvatica, pepperidge, sour gum.

tupelo (noun)	water gum (noun)
any of several gum trees of swampy areas of North America	columnar swamp tree of southeastern to midwestern North America yielding pale soft easily worked wood
pale soft wood of a tupelo tree especially the water gum