EFS is a file-based storage system that is accessed using the NFS protocol.

EFS provides simple, scalable file storage for use with Amazon EC2 instances. Similarly to file servers, or Storage Area Networks or NAS, Amazon EFS provides the ability for users to browse cloud network resources.

EFS can scale to Petabytes and provides low latency access and high level of throughput (MB/s)

Data is stored redundantly across multiple AZs, and can be accessed by up to thousands of Amazon EC2 and other AWS compute instances running in multiple Availability Zones within the same AWS Region.

You can connect from your VPC using mount targets, (network interfaces your instances will use to connect to your file system).

If you have multiple AZ you can create multiple mount targets.

You can even connect across regions (and AWS accounts), in that case you need a Peering connection ( and mount target will use IP Address, not DNS)

EFS

It uses a pay for what you use model with no pre-provisioning required.