whiplash vs whiplash injury

whiplash and whiplash injury both are nouns.

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

As nouns, whiplash and whiplash injury are synonyms defined as:

whiplash and whiplash injury: an injury to the neck (the cervical vertebrae) resulting from rapid acceleration or deceleration (as in an automobile accident)

whiplash (noun)	whiplash injury (noun)
a quick blow delivered with a whip or whiplike object	an injury to the neck (the cervical vertebrae) resulting from rapid acceleration or deceleration (as in an automobile accident)
an injury to the neck (the cervical vertebrae) resulting from rapid acceleration or deceleration (as in an automobile accident)