A Boston shaker consists of two cups/containers that you assemble when mixing the drink, while a Cobbler shaker consists of three parts: a container, a lid with a built-in strainer, and a lid opening. The advantages of a Boston shaker are that it holds more ingredients and is therefore suitable if you want to make several drinks at once. On the other hand, a Cobbler shaker is very easy to handle and popular among beginners, as well as perfect for mixing individual drinks.