OpenShift is an open source, enterprise-grade cloud application platform from Red Hat. It is designed for developers and operations teams to quickly develop, host, and scale applications in a secure and reliable environment. OpenShift provides pre-configured deployment environments for applications of all types, including Java, Ruby, Node.js, PHP, and Python. It also provides a suite of integrated services, such as databases, messaging, caching, and web servers, as well as support for continuous integration, monitoring, and automated deployment. OpenShift is designed to be secure and highly available, with integrated authentication, authorization, and encryption. It also includes developer-friendly features like integrated development environments, command line tools, and an API for automating the deployment and management of applications.
It has many of the same features, but is a micro-platform that allows development teams to use their own hosts in the cloud.
It is capable of handling more complex applications.
CloudStack is about running virtual machines and infrastructure as a service at scale. It is an alternative to OpenStack. OpenShift is a platform-as-a-service that uses Kubernetes, which is containers-as-a-service. So, you can use OpenShift on top of CloudStack just like you can run OpenShift on top of OpenStack. So, CloudStack is not an alternative to OpenShift.
Nanobox is a portable micro platform that can be used with any cloud provider.