Question: what is the difference between add-azureaccount and login-azurermaccount?
Answer: Login-AzureRmAccount is an Alias for Add-AzureRmAccount, so they both do the same thing. Add-AzureAccount is the old service management (classic) command for accessing Azure, which you would use if you needed to access classic resources. Add/Login-AzureRmAccount are for access the new ARM services.