line of business vs line of merchandise

line of business and line of merchandise both are nouns.

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

As nouns, line of business and line of merchandise are synonyms defined as:

line of business and line of merchandise: a particular kind of product or merchandise

Other synonyms of line of business include business line, line, line of products, product line.

line of business (noun)	line of merchandise (noun)
a particular kind of commercial enterprise	a particular kind of product or merchandise
a particular kind of product or merchandise