As nouns,
Icterus galbula bullockii is a hyponym of
Icterus galbula; that is, Icterus galbula bullockii is a
word with a more specific, narrower meaning than
Icterus galbula:
Icterus galbula: a kind of New World oriole
Icterus galbula bullockii: western subspecies of northern oriole