tamarau vs Old World buffalo

tamarau and Old World buffalo both are nouns.

Word	Noun	Adjective	Verb	Adverb
tamarau	Yes	No	No	No
Old World buffalo	Yes	No	No	No

As nouns, Old World buffalo is a hypernym of tamarau; that is, Old World buffalo is a word with a broader meaning than tamarau:

tamarau: small buffalo of Mindoro in the Philippines
Old World buffalo: any of several Old World animals resembling oxen including, e.g., water buffalo, Cape buffalo

Other hypernyms of tamarau include buffalo.

tamarau (noun)	Old World buffalo (noun)
small buffalo of Mindoro in the Philippines	any of several Old World animals resembling oxen including, e.g., water buffalo, Cape buffalo