There are a few key differences between AWS SSO and AWS Cognito. First, AWS SSO is a managed service, while AWS Cognito is a self-service solution. This means that with AWS SSO, you get a dedicated team of experts to help you set up and manage your SSO environment, while with AWS Cognito, you'll need to do everything yourself.
Second, AWS SSO supports multiple identity providers, while AWS Cognito only supports Amazon Cognito Identity. This means that if you want to use AWS SSO, you can use any identity provider that you want, while if you want to use AWS Cognito, you'll be limited to using Amazon Cognito Identity.
Finally, AWS SSO provides a single sign-on experience for your users, while AWS Cognito does not. This means that with AWS SSO, your users will only need to sign in once to access all of the applications that they have been given access to, while with AWS Cognito, they will need to sign in to each application individually.