line of merchandise vs line of products

line of merchandise and line of products both are nouns.

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

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

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

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

line of merchandise (noun)	line of products (noun)
a particular kind of product or merchandise	a particular kind of product or merchandise