marsh marigold vs bog plant

marsh marigold and bog plant both are nouns.

Word	Noun	Adjective	Verb	Adverb
marsh marigold	Yes	No	No	No
bog plant	Yes	No	No	No

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

marsh marigold: 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 marsh marigold include marsh plant, swamp plant.

marsh marigold (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