Outlook and Windows 10 Mail and Calendar are both Microsoft products but differ in complexity and usage. Outlook is a comprehensive, paid tool part of the Microsoft Office suite, offering advanced features like email management rules and integrated task management. It's designed for business use and is available on multiple platforms. On the other hand, Windows 10 Mail and Calendar are separate, simpler, and free applications pre-installed with Windows 10. They offer basic email and calendar functionalities and are primarily designed for personal use on Windows devices.