dotCloud vs IBM Bluemix: What are the differences?
dotCloud: Deploy, manage and scale any web app. Build your ideal application stack by combining powerful cloud services. Experiment for free, then go live and only pay for what you need. dotCloud enables developers and IT organizations to deploy, manage and scale their applications with unprecedented ease and flexibility by assembling and customizing powerful pre-configured stacks and services; IBM Bluemix: *A cloud platform as a service *. It is an open standards, cloud platform for building, running, and managing apps and services. It supports several programming languages and services as well as integrated DevOps to build, run, deploy and manage applications on the cloud.
dotCloud and IBM Bluemix can be primarily classified as "Platform as a Service" tools.