While both cocktail shakers and blenders are used to mix drinks, they serve different purposes. A cocktail shaker is primarily used for combining ingredients and chilling the drink by incorporating ice. It is ideal for creating shaken cocktails with a smooth and balanced texture. On the other hand, a blender is designed to blend ingredients together, creating a more uniform and blended consistency. Blenders are often used for frozen cocktails or drinks that require the incorporation of ice or frozen fruits.