international pitch vs concert pitch

international pitch and concert pitch both are nouns.

Word	Noun	Adjective	Verb	Adverb
international pitch	Yes	No	No	No
concert pitch	Yes	No	No	No

As nouns, international pitch and concert pitch are synonyms defined as:

international pitch and concert pitch: the pitch used to tune instruments for concert performances; usually assigns 440 Hz to the A above middle C

Other synonyms of international pitch include philharmonic pitch.

international pitch (noun)	concert pitch (noun)
the pitch used to tune instruments for concert performances; usually assigns 440 Hz to the A above middle C	the pitch used to tune instruments for concert performances; usually assigns 440 Hz to the A above middle C