fluoresceine vs eosin

fluoresceine and eosin both are nouns.

Word	Noun	Adjective	Verb	Adverb
fluoresceine	Yes	No	No	No
eosin	Yes	No	No	No

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

fluoresceine: a yellow dye that is visible even when highly diluted; used as an absorption indicator when silver nitrate solution is added to sodium chloride in order to precipitate silver chloride (turns pink when no chloride ions are left in solution and negative fluorescein ions are then absorbed)
eosin: a red fluorescent dye resulting from the action of bromine on fluorescein; used in cosmetics and as a biological stain for studying cell structures

Other hyponyms of fluoresceine include bromeosin.

fluoresceine (noun)	eosin (noun)
a yellow dye that is visible even when highly diluted; used as an absorption indicator when silver nitrate solution is added to sodium chloride in order to precipitate silver chloride (turns pink when no chloride ions are left in solution and negative fluorescein ions are then absorbed)	a red fluorescent dye resulting from the action of bromine on fluorescein; used in cosmetics and as a biological stain for studying cell structures