merger vs uniting

merger and uniting both are nouns.

Word	Noun	Adjective	Verb	Adverb
merger	Yes	No	No	No
uniting	Yes	No	No	No

As nouns, merger and uniting are synonyms defined as:

Other synonyms of merger include amalgamation.

merger (noun)	uniting (noun)
the combination of two or more commercial companies	the act of making or becoming a single unit
an occurrence that involves the production of a union	the combination of two or more commercial companies