What is this all about? It took me a bit of digging, but what it boils down to is that Microsoft made a fundamental change to how things are managed within Azure. You will now find documentation on these two different deployment models: Classic Deployments and Resource Manager Deployments. These two different set of Powershell cmdlets reflect these different models, as anything for Classic Deployments are handled by cmdlets in the Azure and Azure.Storage modules. All the Resource Manager Deployment stuff is handled by the AzureRM* modules.
This is the first in a series and serves as an introduction to the topic.