Original: Aneurysms can commonly occur in arteries at the base of the brain (the circle of Willis) and an aortic aneurysm occurs in the main artery carrying blood from the left ventricle of the heart.
Simplified: Aneurysms usually happen in arteries at the base of the brain and in the aorta (the main artery coming out of the heart) - this is an aortic aneurysm.