school year vs academic year

school year and academic year both are nouns.

Word	Noun	Adjective	Verb	Adverb
school year	Yes	No	No	No
academic year	Yes	No	No	No

As nouns, school year and academic year are synonyms defined as:

school year and academic year: the period of time each year when the school is open and people are studying

school year (noun)	academic year (noun)
the period of time each year when the school is open and people are studying	the period of time each year when the school is open and people are studying