If you need to deploy Azure Stack as a company already using Windows Azure Pack, there are some points you should think about to make life easier. Both solutions use different portals and technologies today; Azure Pack is based on System Center and Windows Server, while Azure Stack is Azure technology.

If you want to deploy Azure Stack and connect your tenant clouds running on Azure Pack to Azure Stack, the easiest way is to configure Azure Pack to authenticate using Azure AD or even ADFS. This means that regardless of the portal that the tenants are using, the same authentication account is being used.

The next step is to think about the implementation of the WAP connector for Azure Stack as this connector gives you a way to start, and stop resources within one portal, and this one is the new Azure Stack portal. You will be able to switch between clouds and connect from your Azure Stack portal to the resources running on Azure Pack (WAP). This connector will be part of your Azure Stack deployment, if you need it, but as a prerequisite, we need to run the latest update rollup package with Azure Pack to enable the web service required in Azure Pack to allow connections from Azure Stack.

If you're thinking about migrating resources from a WAP cloud to an Azure Stack cloud, I clearly recommend planning a smooth migration of services (step by step). This means you should look with your tenant at each service (for example, SharePoint, Exchange, and CRM) and plan a transition to a new server, maybe with the chance to move to a new release of the currently running service (for example, each release of 2016). After all, resources of one cloud have been migrated to the Azure Stack cloud you could dismiss the Azure Pack cloud. If all clouds are being migrated to Azure Stack, you could completely tear down your Azure Pack implementation.

Another way to migrate services from Azure Pack to Azure Stack is using the Azure Site Recovery (ASR). So you will need to migrate the existing resources to Azure (using ASR) and then from Azure back to Azure Stack. To make this happen, there needs to be support for Azure Stack in ASR.

Regardless of all the previous steps, you need to decide whether you want the AAD-connected or the ADFS-disconnected scenario.