noun
Kuril Islands
Refers to the volcanic archipelago stretching from Hokkaido to Kamchatka. Often used in geographical, political, and news contexts.
千島列島は北海道の北東に位置する。
The Kuril Islands are located northeast of Hokkaido.
北方領土 refers specifically to the disputed Southern Kuril Islands (Etorofu, Kunashiri, Shikotan, Habomai), while 千島列島 is the entire island chain.
千島 (Chishima, 'thousand islands') + 列島 (rettō, 'archipelago'). The name is a direct Japanese description of the numerous islands in the chain.