horizontal integration vs horizontal combination

horizontal integration and horizontal combination both are nouns.

Word	Noun	Adjective	Verb	Adverb
horizontal integration	Yes	No	No	No
horizontal combination	Yes	No	No	No

As nouns, horizontal integration and horizontal combination are synonyms defined as:

horizontal integration and horizontal combination: absorption into a single firm of several firms involved in the same level of production and sharing resources at that level

horizontal integration (noun)	horizontal combination (noun)
absorption into a single firm of several firms involved in the same level of production and sharing resources at that level	absorption into a single firm of several firms involved in the same level of production and sharing resources at that level