eland vs giant eland

eland and giant eland both are nouns.

Word	Noun	Adjective	Verb	Adverb
eland	Yes	No	No	No
giant eland	Yes	No	No	No

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

eland: either of two large African antelopes of the genus Taurotragus having short spirally twisted horns in both sexes
giant eland: large dark striped eland of western equatorial Africa

Other hyponyms of eland include common eland, Taurotragus oryx, Taurotragus derbianus.

eland (noun)	giant eland (noun)
either of two large African antelopes of the genus Taurotragus having short spirally twisted horns in both sexes	large dark striped eland of western equatorial Africa