Yes, it adds a new custom types AWS::Serverless::* [1] and new Globals section [2] and it is really pleasant to work with for basic, not complicated API. It is transformed into CF template via samtranslator [3] (recently open-sourced) so it inherits a lot from CloudFormation but also that's why I encountered differences between SAM and CF types.

[1]: https://awslabs.github.io/serverless-application-model/inter...

[2]: https://awslabs.github.io/serverless-application-model/globa...

[3]: https://github.com/awslabs/serverless-application-model/tree...