crossbreeding vs pairing

crossbreeding and pairing both are nouns.

Word	Noun	Adjective	Verb	Adverb
crossbreeding	Yes	No	No	No
pairing	Yes	No	No	No

As nouns, pairing is a hypernym of crossbreeding; that is, pairing is a word with a broader meaning than crossbreeding:

crossbreeding: (genetics) the act of mixing different species or varieties of animals or plants and thus to produce hybrids
pairing: the act of pairing a male and female for reproductive purposes

Other hypernyms of crossbreeding include conjugation, coupling, mating, sexual union, union.

crossbreeding (noun)	pairing (noun)
(genetics) the act of mixing different species or varieties of animals or plants and thus to produce hybrids	the act of pairing a male and female for reproductive purposes
reproduction by parents of different races (especially by white and non-white persons)	the act of grouping things or people in pairs