When an EC2 instance store-backed AMI is launched, all the parts have to be retrieved from S3 before the instance is available. With an EBS-backed AMI is launched, parts are lazily loaded and only the parts required to boot the instance need to be retrieved from the snapshot before the instance is available.  

EBS volumes preserve their data through instance stops and terminations.

You can back up EBS volumes with EBS snapshots.

You can remove EBS volumes from one instance, and reattach them to another.

EBS volumes support full-volume encryption.