waterbuck vs kob

waterbuck and kob both are nouns.

Word	Noun	Adjective	Verb	Adverb
waterbuck	Yes	No	No	No
kob	Yes	No	No	No

As nouns, kob is a hyponym of waterbuck; that is, kob is a word with a more specific, narrower meaning than waterbuck:

waterbuck: any of several large African antelopes of the genus Kobus having curved ridged horns and frequenting e.g. swamps and rivers
kob: an orange-brown antelope of southeast Africa

Other hyponyms of waterbuck include Kobus kob, Kobus leche, lechwe.

waterbuck (noun)	kob (noun)
any of several large African antelopes of the genus Kobus having curved ridged horns and frequenting e.g. swamps and rivers	an orange-brown antelope of southeast Africa