althaea vs marsh mallow

althaea and marsh mallow both are nouns.

Word	Noun	Adjective	Verb	Adverb
althaea	Yes	No	No	No
marsh mallow	Yes	No	No	No

As nouns, marsh mallow is a hyponym of althaea; that is, marsh mallow is a word with a more specific, narrower meaning than althaea:

althaea: any of various plants of the genus Althaea; similar to but having smaller flowers than genus Alcea
marsh mallow: European perennial plant naturalized in United States having triangular ovate leaves and lilac-pink flowers

Other hyponyms of althaea include Althea officinalis, white mallow.

althaea (noun)	marsh mallow (noun)
any of various plants of the genus Althaea; similar to but having smaller flowers than genus Alcea	European perennial plant naturalized in United States having triangular ovate leaves and lilac-pink flowers