what is the difference between dedicated instance and dedicated host?

Dedicated instance is an EC2 instance that runs on hardware dedicated to a single AWS account, but you don’t control the physical server.
Dedicate host is a physical server fully dedicated to your AWS account. You have full control over the host and can place multiple EC2 instances on it.

What is FQDN?

he full name of a computer on the internet, including all domains up to the top-level domain.

What is FQDN?

what is the difference between dedicated instance and dedicated host?

Where are EBS snapshots stored?

the snapshots are stored in multiple availability zones through amazon s3 for long term retention.