API documentation and API specification, while closely related, serve distinct purposes. API documentation is a comprehensive guide that educates developers on how to effectively use and integrate with an API. It covers details such as endpoints, parameters, sample requests, and responses. On the other hand, API specification provides a technical blueprint of the API. It defines the functionalities, structures, and constraints of the API, often written using languages like OpenAPI or RAML. While documentation is geared towards the API's users, the specification is more for the API's designers and developers.