retail store vs sales outlet

retail store and sales outlet both are nouns.

Word	Noun	Adjective	Verb	Adverb
retail store	Yes	No	No	No
sales outlet	Yes	No	No	No

As nouns, retail store and sales outlet are synonyms defined as:

Other synonyms of retail store include mercantile establishment, outlet.

retail store (noun)	sales outlet (noun)
a place of business for retailing goods	a place of business for retailing goods