trading post vs sales outlet

trading post and sales outlet both are nouns.

Word	Noun	Adjective	Verb	Adverb
trading post	Yes	No	No	No
sales outlet	Yes	No	No	No

As nouns, sales outlet is a hypernym of trading post; that is, sales outlet is a word with a broader meaning than trading post:

trading post: a retail store serving a sparsely populated region; usually stocked with a wide variety of merchandise
sales outlet: a place of business for retailing goods

Other hypernyms of trading post include mercantile establishment, outlet, retail store.

trading post (noun)	sales outlet (noun)
a retail store serving a sparsely populated region; usually stocked with a wide variety of merchandise	a place of business for retailing goods