As nouns,
Ursus arctos is a hypernym of
Ursus arctos middendorffi; that is, Ursus arctos is a
word with a broader meaning than Ursus arctos middendorffi:
Ursus arctos middendorffi: brown bear of coastal Alaska and British Columbia
Ursus arctos: large ferocious bear of Eurasia
Other hypernyms of Ursus arctos middendorffi include
brown bear, bruin.