loner vs solitary

loner and solitary both are nouns.

Word	Noun	Adjective	Verb	Adverb
loner	Yes	No	No	No
solitary	Yes	Yes	No	No

As nouns, solitary is a hyponym of loner; that is, solitary is a word with a more specific, narrower meaning than loner:

Other hyponyms of loner include hermit, recluse, solitudinarian, troglodyte.

loner (noun)	solitary (noun)
a person who avoids the company or assistance of others	one who lives in solitude
	confinement of a prisoner in isolation from other prisoners

loner (adjective)	solitary (adjective)
	being the only one; single and isolated from others
	lacking companions or companionship
	of plants and animals; not growing or living in groups or colonies
	devoid of creatures
	characterized by or preferring solitude