CBD oil and hemp oil are not the same thing¹.
Hemp oil or hemp seed oil comes from pressing the seeds of the hemp plant, rather than from full-grown specimens. Prior to cannabis plants becoming illegal, hemp seed oil was used to produce paints, inks, varnishes, and other materials. This oil contains neither THC nor CBD. As industrial hemp pilot programs take off, hemp oil has become a viable source of fatty acids for food supplements, birdseed, soap, and beauty products.
CBD oil contains cannabidiol and often other hemp products, such as terpenes and other cannabinoids. The oil part of CBD oil does not always come from the hemp plant. Instead, some manufacturers use coconut oil, adding the materials extracted from the hemp plant to separately extracted oil. Hemp seed oil does see use as a CBD carrier oil, however. Reputable manufacturers will specify their carrier oil on the product page as well as on the packaging of the product itself.