elephant yam vs arum

elephant yam and arum both are nouns.

Word	Noun	Adjective	Verb	Adverb
elephant yam	Yes	No	No	No
arum	Yes	No	No	No

As nouns, arum is a hypernym of elephant yam; that is, arum is a word with a broader meaning than elephant yam:

elephant yam: putrid-smelling aroid of southeastern Asia (especially the Philippines) grown for its edible tuber
arum: any plant of the family Araceae; have small flowers massed on a spadix surrounded by a large spathe

Other hypernyms of elephant yam include aroid.

elephant yam (noun)	arum (noun)
putrid-smelling aroid of southeastern Asia (especially the Philippines) grown for its edible tuber	any plant of the family Araceae; have small flowers massed on a spadix surrounded by a large spathe
	starch resembling sago that is obtained from cuckoopint root