Systems Manager helps you automatically collect software inventory, apply OS patches, create system images, and configure Windows and Linux operating systems.
CloudFormation is an Infrastructure as Code (IaC) product — you can create manage, and remove infrastructure using JSON or YAML. CloudFormation is effective if you frequently deploy the same infrastructure or you require guaranteed consistent configuration.
OpsWorks is an implementation of the Chef configuration management and deployment platform. OpsWorks moves away from the low-level configurability of CloudFormation but not as far as Elastic Beanstalk. OpsWorks lets you create a stack of resources with layers and manage resources as a unit.
Elastic Beanstalk (EB) is a Platform as a Service product. It allows you to deploy code and, with very little effort or modifications, the service will provision the infrastructure on your behalf.
Elastic Beanstalk handles provisioning, monitoring, Auto Scaling, load balancing, and software updating for you — you just worry about the cost.