couturier vs designer

couturier and designer both are nouns.

Word	Noun	Adjective	Verb	Adverb
couturier	Yes	No	No	No
designer	Yes	No	No	No

As nouns, couturier and designer are synonyms defined as:

Other synonyms of couturier include clothes designer, fashion designer.

couturier (noun)	designer (noun)
someone who designs clothing	someone who creates plans to be used in making something (such as buildings)
	someone who designs clothing
	a person who specializes in interior design
	a person who devises plots or intrigues
	someone who specializes in graphic design