line of business vs product

line of business and product both are nouns.

Word	Noun	Adjective	Verb	Adverb
line of business	Yes	No	No	No
product	Yes	No	No	No

As nouns, product is a hypernym of line of business; that is, product is a word with a broader meaning than line of business:

Other hypernyms of line of business include merchandise, ware.

line of business (noun)	product (noun)
a particular kind of commercial enterprise	an artifact that has been created by someone or some process
a particular kind of product or merchandise	items for sale to the individual consumer
	a quantity obtained by multiplication
	the set of elements common to two or more sets
	a consequence of someone's efforts or of a particular set of circumstances
	a chemical substance formed as a result of a chemical reaction