What is the difference between Exchange Web services and Outlook on the Web?

Can you clarify the distinction between Exchange Web Services and Outlook on the Web for me? I understand they both involve email and calendaring functionalities, but I'm unsure of the precise differences in their capabilities and how they operate. Are they interchangeable, or do they serve distinct purposes within an organization's digital infrastructure? I'm interested in understanding the nuances of each service and how they may be Leveraged to enhance collaboration and productivity.