hydathode vs stoma

hydathode and stoma both are nouns.

Word	Noun	Adjective	Verb	Adverb
hydathode	Yes	No	No	No
stoma	Yes	No	No	No

As nouns, stoma is a hypernym of hydathode; that is, stoma is a word with a broader meaning than hydathode:

hydathode: a pore that exudes water on the surface or margin of a leaf of higher plants
stoma: a minute epidermal pore in a leaf or stem through which gases and water vapor can pass

Other hypernyms of hydathode include pore, stomate.

hydathode (noun)	stoma (noun)
a pore that exudes water on the surface or margin of a leaf of higher plants	a mouth or mouthlike opening (especially one created by surgery on the surface of the body to create an opening to an internal organ)
	a minute epidermal pore in a leaf or stem through which gases and water vapor can pass