shopping mall vs sales outlet

shopping mall and sales outlet both are nouns.

Word	Noun	Adjective	Verb	Adverb
shopping mall	Yes	No	No	No
sales outlet	Yes	No	No	No

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

shopping mall: mercantile establishment consisting of a carefully landscaped complex of shops representing leading merchandisers; usually includes restaurants and a convenient parking area; a modern version of the traditional marketplace
sales outlet: a place of business for retailing goods

Other hypernyms of shopping mall include mercantile establishment, outlet, retail store.

shopping mall (noun)	sales outlet (noun)
mercantile establishment consisting of a carefully landscaped complex of shops representing leading merchandisers; usually includes restaurants and a convenient parking area; a modern version of the traditional marketplace	a place of business for retailing goods