Cognito User Pool vs Identity Pools

• A Cognito User Pool is a table of users with ids and other metadata about the user.
• An Identity Pool is a mapping from the user id in a User Pool to an IAM role that allows that user to access other AWS services, like S3 or DynamoDB

So User Pools store your users (a user pool client will let users sign up), and Identity Pools are how you give those users permission to do things.