EFS is a managed network file system (NFS) that can be mounted on many EC2 instances, even across AZs. Highlighy available and scalable, but it is expensive.
Useful for CMS, web servers, etc. Linux only AMIs, and uses NFSv4.
Supports encryption at rest using KMS.
Scales automatically, pay for the storage you use.
Really high performance, and can be controlled: general purpose or max I/O.
Has different storage tiers, including lifecycle management support. Pick between standard and infrequently accessed (IA).
In contrast, [[EBS]] is tied to a single EC2 instance.