Amazon Web Services vs. Google Cloud Platform
Running An Email Server
cannot create an outbound TCP connection to port 25
from a GCE instance. This means that, practically, you cannot run a standard
email server (like Postfix on Linux)
on your Google Compute Engine instance. On the other side, AWS does not
have such a restriction for long time customers and also Amazon
allows you to configure
Reverse DNS records
for any of your
Elastic (=static) IP addresses, which is a plus for
users that want to run their own legitimate email servers in their
Running VPN Server
There are various VPN server software that can run within in an instance. The simplest (but also obsolete, due to its security weaknesses) is the one that uses PPTP. A PPTP tunnel is instantiated by communication to the peer on TCP port 1723. This TCP connection is then used to initiate and manage a second GRE tunnel to the same peer. However, the GRE protocol is not supported by Google, so you cannot use PPTP in a GCE instance. Amazon does not have this restriction in its EC2-VPC.
Amazon has full support for IPv6 on most platforms, including their virtual servers (EC2). Google has no support for IPv6 on all regions yet.
IP Address Pricing
Generally, cloud providers do not charge for the first real (external) IP address assigned and used on a virtual machine. This was true for AWS and GCP until the end of 2019. However, Google announced that IP addresses will be charged roughly 2.90 USD per month starting with 2020.