Cognito

Decentralized managed authentication. Sign-up, sign-in integration for your apps. Social identity provider eg. Facebook, Google.

User pools, allows users to authenticate using OAuth to IpD such as Facebook, Google, Amazone ... to connect to web-applications. Cognito User Pool is in itself a IpD, they use JWTs for persisting authentication

Identity pools provides temporary AWS credentials to access services like S3 and DynamoDB

Sync can sync user data and preferences across devices with one line of code (powerd by SNS)

Web Identity Federation exchange identity and security information between Identity provider (IdP) and an application

Identity Provider (IdP) a trusted provider for your user identity that lets you use authenticate to access other services eg. Facebook

OIDC is a type of identity provider which user OAuth

SAML is a type of identity provider which is used for Single Sign-on (SS0)