Hi river453.
Your ask is not as easy to answer as you’d think, as you are comparing 2 entirely different solutions.
With EC2, you can import single VMs and have them run on EC2 instances.
VMware Cloud in AWS is quite the opposite, as you will have a full SDDC at your hands. The entire SDDC is maintained by VMware and it is more of an IaaS offering.
Besides, you can seamlessly migrate your VMs from on-premises into the cloud - and back! Even with a live vMotion, so no downtime needed.
For EC2, you’d need to import the VM. Powered off. The same goes for the export. There is no ‘vMotion’ capability with native EC2.
A real world example: Have your consuming VMs readily available on VMC, like AD and webservers, VDI workload, ..
Let’s assume the webservers rely on a (big) DB. You could then think of leveraging Amazons RDS for the same. With VMC, since it is attached to your AWS VPC, you’ll have a fast connection from your workload on VMC into the DB service offered by AWS. Quite a few customers ‘mix’ native AWS services that way with VMC. (This also applies to S3 and many other AWS services).
I hope this answer helps a little bit, to understand the difference of the offerings available.