house wren vs jenny wren

house wren and jenny wren both are nouns.

Word	Noun	Adjective	Verb	Adverb
house wren	Yes	No	No	No
jenny wren	Yes	No	No	No

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

house wren: common American wren that nests around houses
jenny wren: any of several small active brown birds of the Northern Hemisphere with short upright tails; they feed on insects

Other hypernyms of house wren include wren.

house wren (noun)	jenny wren (noun)
common American wren that nests around houses	any of several small active brown birds of the Northern Hemisphere with short upright tails; they feed on insects