Caltha palustris vs bog plant

Caltha palustris and bog plant both are nouns.

Word	Noun	Adjective	Verb	Adverb
Caltha palustris	Yes	No	No	No
bog plant	Yes	No	No	No

As nouns, bog plant is a hypernym of Caltha palustris; that is, bog plant is a word with a broader meaning than Caltha palustris:

Caltha palustris: swamp plant of Europe and North America having bright yellow flowers resembling buttercups
bog plant: a semiaquatic plant that grows in soft wet land; most are monocots: sedge, sphagnum, grasses, cattails, etc; possibly heath

Other hypernyms of Caltha palustris include marsh plant, swamp plant.

Caltha palustris (noun)	bog plant (noun)
swamp plant of Europe and North America having bright yellow flowers resembling buttercups	a semiaquatic plant that grows in soft wet land; most are monocots: sedge, sphagnum, grasses, cattails, etc; possibly heath