salary increase vs hike

salary increase and hike both are nouns.

Word	Noun	Adjective	Verb	Adverb
salary increase	Yes	No	No	No
hike	Yes	No	Yes	No

As nouns, salary increase and hike are synonyms defined as:

Other synonyms of salary increase include raise, rise, wage hike, wage increase.

salary increase (noun)	hike (noun)
the amount a salary is increased	a long walk usually for exercise or pleasure
	the amount a salary is increased
	an increase in cost

salary increase (verb)	hike (verb)
	walk a long way, as for pleasure or physical exercise
	increase