salary increase vs wage increase

salary increase and wage increase both are nouns.

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

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

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

salary increase (noun)	wage increase (noun)
the amount a salary is increased	the amount a salary is increased