service cap vs yachting cap

service cap and yachting cap both are nouns.

Word	Noun	Adjective	Verb	Adverb
service cap	Yes	No	No	No
yachting cap	Yes	No	No	No

As nouns, service cap and yachting cap are synonyms defined as:

service cap and yachting cap: a cap with a flat circular top and a visor

Other synonyms of service cap include kepi, peaked cap.

service cap (noun)	yachting cap (noun)
a cap with a flat circular top and a visor	a cap with a flat circular top and a visor