line of merchandise vs line of business

line of merchandise and line of business both are nouns.

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

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

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

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

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