buy vs travel bargain

buy and travel bargain both are nouns.

Word	Noun	Adjective	Verb	Adverb
buy	Yes	No	Yes	No
travel bargain	Yes	No	No	No

As nouns, travel bargain is a hyponym of buy; that is, travel bargain is a word with a more specific, narrower meaning than buy:

buy: an advantageous purchase
travel bargain: a bargain rate for travellers on commercial routes (usually air routes)

Other hyponyms of buy include song.

buy (noun)	travel bargain (noun)
an advantageous purchase	a bargain rate for travellers on commercial routes (usually air routes)

buy (verb)	travel bargain (verb)
accept as true
obtain by purchase; acquire by means of a financial transaction
make illegal payments to in exchange for favors or influence
acquire by trade or sacrifice or exchange
be worth or be capable of buying