Troglodytes troglodytes vs wren

Troglodytes troglodytes and wren both are nouns.

Word	Noun	Adjective	Verb	Adverb
Troglodytes troglodytes	Yes	No	No	No
wren	Yes	No	No	No

As nouns, wren is a hypernym of Troglodytes troglodytes; that is, wren is a word with a broader meaning than Troglodytes troglodytes:

Troglodytes troglodytes: small wren of coniferous forests of Northern Hemisphere
wren: any of several small active brown birds of the Northern Hemisphere with short upright tails; they feed on insects

Other hypernyms of Troglodytes troglodytes include jenny wren.

Troglodytes troglodytes (noun)	wren (noun)
small wren of coniferous forests of Northern Hemisphere	any of several small active brown birds of the Northern Hemisphere with short upright tails; they feed on insects