There are three types of storage gateways:

File Gateway (NFS): Using NFS, store flat files in S3 e.g word etc.

Volume Gateways (iSCSI): This is using block-based storage Stored volumes: you would store the entire copy of your site data on AWS Cached volumes: this is where you are only storing the most recently accessed data. i.e. you would use this if you want AWS as your privacy reading resources

Tape Gateway (VTL): Back up and archiving solution allows you to create virtual tapes and send them to S3

Date written to these volumes can be asynchronously backed up as point in time snapshots of your volumes, and stored in the cloud as EBS snapshots.

Snapshots are incremented backups that capture only change blocks.