barter vs horse trading

barter and horse trading both are nouns.

Word	Noun	Adjective	Verb	Adverb
barter	Yes	No	Yes	No
horse trading	Yes	No	No	No

As nouns, horse trading is a hyponym of barter; that is, horse trading is a word with a more specific, narrower meaning than barter:

Other hyponyms of barter include horse trade.

barter (noun)	horse trading (noun)
an equal exchange	the swapping of horses (accompanied by much bargaining)
	negotiation accompanied by mutual concessions and shrewd bargaining

barter (verb)	horse trading (verb)
exchange goods without involving money