sport coat vs sports jacket

sport coat and sports jacket both are nouns.

Word	Noun	Adjective	Verb	Adverb
sport coat	Yes	No	No	No
sports jacket	Yes	No	No	No

As nouns, sport coat and sports jacket are synonyms defined as:

sport coat and sports jacket: lightweight single-breasted jacket; often striped in the colors of a club or school

Other synonyms of sport coat include blazer, sport jacket, sports coat.

sport coat (noun)	sports jacket (noun)
lightweight single-breasted jacket; often striped in the colors of a club or school	lightweight single-breasted jacket; often striped in the colors of a club or school