For a better understanding of the ARM model, you might need to consider the following key points:

• Resources with the same lifecycle should be gathered in the same resource group
• Resources in different regions can be in the same resource group
• Every resource must be assigned to a resource group, so whenever you want to move a resource between resource groups you must remove it from its current resource group and then add it to the new resource group
• Resource groups support RBAC, wherein a user can have access to some specific resources, and have no access to the others
• Some resources can be shared across resource groups such as storage accounts
• ARM virtual machines can only be placed in ARM storage accounts
• You cannot create a virtual machine using the ARM model and assign it to a virtual network built using the ASM model
• You cannot use a prebuilt image that was created by ASM APIs to build a VM using the ARM model, but as a workaround you can copy the VHD files from the storage account in the classic portal to a storage account created in the ARM model
• You can migrate assets from the ASM model to the ARM model
• Every resource must be assigned to a resource group, so whenever you want to move a resource between resource groups you must remove it from its current resource group, and then add it to the new resource group