Web Map Server vs Web Map Service

Web Map Server and Web Map Service both are nouns.

Word	Noun	Adjective	Verb	Adverb
Web Map Server	Yes	No	No	No
Web Map Service	Yes	No	No	No

As nouns, Web Map Server and Web Map Service are synonyms defined as:

Web Map Server and Web Map Service: a computer program that produces maps of spatially referenced data dynamically from geographic information

Web Map Server (noun)	Web Map Service (noun)
a computer program that produces maps of spatially referenced data dynamically from geographic information	a computer program that produces maps of spatially referenced data dynamically from geographic information