isn’t it true, that there are certain operations or functions only available from one outlet vs. the others, that is maybe I can only do it via the Azure CLI, not the portal or via the CLI I have more controls and options? and what IaC tool would you recommend best to use with Azure?
While Microsoft does a great job of keeping parity between the Azure CLI, PowerShell and the Azure Portal, it can happen that a new feature is implemented in one before the others. All three connect to the Azure REST API, so they will all have access to the exact same features.
Any Azure user might have their own preference of method and tool, which can then appear to have more features. If you are a master at the CLI, you would tend to use that for complex scenarios rather than PowerShell for example.
In terms of your question for IaC (infrastructure as code) tool, I’d recommend learning to use Azure Resource Manager (ARM) templates at first to get a good understanding of the approach. If you are after a more multi-cloud approach, Terraform is a great option too.
I hope that helps.