Japanese leaf vs houseplant

Japanese leaf and houseplant both are nouns.

Word	Noun	Adjective	Verb	Adverb
Japanese leaf	Yes	No	No	No
houseplant	Yes	No	No	No

As nouns, houseplant is a hypernym of Japanese leaf; that is, houseplant is a word with a broader meaning than Japanese leaf:

Japanese leaf: erect or partially climbing herb having large green or variegated leaves
houseplant: any of a variety of plants grown indoors for decorative purposes

Japanese leaf (noun)	houseplant (noun)
erect or partially climbing herb having large green or variegated leaves	any of a variety of plants grown indoors for decorative purposes