accident vs injury

accident and injury both are nouns.

Word	Noun	Adjective	Verb	Adverb
accident	Yes	No	No	No
injury	Yes	No	No	No

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

Other hyponyms of accident include collision, crash, wreck, accidental injury, shipwreck, wreck, casualty, fatal accident.

accident (noun)	injury (noun)
anything that happens suddenly or by chance without an apparent cause	wrongdoing that violates another's rights and is unjustly inflicted
an unfortunate mishap; especially one causing damage or injury	an act that causes someone or something to receive physical damage
	an accident that results in physical damage or hurt
	a casualty to military personnel resulting from combat
	any physical damage to the body caused by violence or accident or fracture etc.; the condition of an injury