vertical integration vs vertical combination

vertical integration and vertical combination both are nouns.

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

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

vertical integration and vertical combination: absorption into a single firm of several firms involved in all aspects of a product's manufacture from raw materials to distribution

vertical integration (noun)	vertical combination (noun)
absorption into a single firm of several firms involved in all aspects of a product's manufacture from raw materials to distribution	absorption into a single firm of several firms involved in all aspects of a product's manufacture from raw materials to distribution