sedge wren vs marsh wren

sedge wren and marsh wren both are nouns.

Word	Noun	Adjective	Verb	Adverb
sedge wren	Yes	No	No	No
marsh wren	Yes	No	No	No

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

sedge wren (noun)	marsh wren (noun)
small European warbler that breeds among reeds and wedges and winters in Africa	a wren of the genus Cistothorus that frequents marshes
small American wren inhabiting wet sedgy meadows