The main differences between the carotid artery and the vertebral artery are: i. The carotid artery branches from the common carotid artery and travels laterally in the cervical spine, while the vertebral artery branches from the subclavian artery and travels in the intervertebral foramen. The carotid artery enters the skull through the carotid canal, and the vertebral artery enters the skull through the foramen magnum of the occipital bone. Third, the carotid artery supplies blood to the front 2/3 of the brain, and the vertebral artery supplies blood to the back 1/3 of the brain. Fourth, the carotid artery has a thicker diameter and the vertebral artery has a thinner diameter. The carotid artery and the vertebral artery together form the Wills ring in the brain, supplying the entire brain. The carotid artery is more clinically significant than the vertebral artery, causing obvious symptoms of cerebral ischemia when the carotid artery is narrowed, while the vertebral artery is thinner, so it is often compensated by the carotid artery without symptoms.