yachting cap vs service cap

yachting cap and service cap both are nouns.

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

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

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

Other synonyms of yachting cap include kepi, peaked cap.

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