What is a key difference between SAML and OAuth?

The distinction between SAML and OAuth lies primarily in their intended purposes and functionalities within identity and access management frameworks. SAML (Security Assertion Markup Language) is designed specifically for authentication, allowing a user to log in once and gain access to multiple applications without needing to provide credentials again. It facilitates Single Sign-On (SSO) by securely transmitting user identity information between identity providers and service providers.

On the other hand, OAuth (Open Authorization) is primarily concerned with authorization. It allows third-party applications to gain limited access to a user's resources without exposing their credentials. For instance, an application can request permission to access certain information from another service on behalf of the user, using tokens that specify what can be accessed and under what conditions, rather than dealing directly with user passwords.

This clear division of responsibilities—SAML focusing on authenticating users and OAuth managing access to resources—highlights the different use cases and implementation scenarios for these two protocols. Understanding this nuance is essential for integrating them effectively within security architectures.