yearn vs ache

yearn is not a noun while ache is a noun.

Word	Noun	Adjective	Verb	Adverb
yearn	No	No	Yes	No
ache	Yes	No	Yes	No

As verbs, ache is a hyponym of yearn; that is, ache is a word with a more specific, narrower meaning than yearn:

Other hyponyms of yearn include languish, pine, yearn, yen.

As verbs, yearn and ache are synonyms defined as:

yearn and ache: have a desire for something or someone who is not present

Other synonyms of yearn include languish, pine, yen.

yearn (noun)	ache (noun)
	a dull persistent (usually moderately intense) pain

yearn (verb)	ache (verb)
desire strongly or persistently	have a desire for something or someone who is not present
have a desire for something or someone who is not present	be the source of pain
have affection for; feel tenderness for	feel physical pain