SAM to define serverless applications in simple and clean syntax. For example, in SAM "Cors" can be enabled with just one property , which will translate to whole blocks of codes in CloudFormation template.
Translates SAM templates into AWS CloudFormation stacks, filling in default values for any unspecified properties and determining the appropriate mappings and invocation permissions
Describes Lambda functions, API endpoints and the other resources
Can also use conventional AWS CloudFormation syntax for expressing resources in the same template. Any resources not included in the current SAM model can still be created in the AWS CloudFormation template using AWS CloudFormation syntax. In addition, you can use AWS CloudFormation syntax to express serverless resources as an alternative to using the SAM model.