VM instance in GCP is quite similar to AWS EC2. You can choose from a variety of machine (instance) types that have different hardware configurations. As well as OS images that are Linux or Windows–based OS or your customized OS, you can choose.
As mentioned when talking about firewall rules, you can specify zero or more network tags. A tag is not necessary to be created beforehand. This means you can launch VM instances with network tags first, even though a firewall rule is not created. It is still valid, but no firewall rule is applied in this case. Then create a firewall rule to have a network tag. Eventually a firewall rule will be applied to the VM instances afterwards. This is why VM instances and firewall rules are loosely ...
