green algae vs desmid

green algae and desmid both are nouns.

Word	Noun	Adjective	Verb	Adverb
green algae	Yes	No	No	No
desmid	Yes	No	No	No

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

green algae: algae that are clear green in color; often growing on wet ricks or damp wood or the surface of stagnant water
desmid: freshwater green algae

Other hyponyms of green algae include laver, sea lettuce, pond scum, spirogyra, stonewort.

green algae (noun)	desmid (noun)
algae that are clear green in color; often growing on wet ricks or damp wood or the surface of stagnant water	freshwater green algae