EFS vs. EBS Content Ma

At a high-level, EBS is best thought of as a hard disk in the cloud. It's directly attached to the host, and can only be attached to a single host at a time (EBS multi-attach notwithstanding https://docs.aws.amazon.com/ebs/latest/userguide/ebs-volumes-multi.html )

EFS is elastic and scalable, can be shared between multiple instances, and is attached to each EC2 instance over IP, using NFS.

EBS tends to be faster, and better when your use case calls for high-performnace block storage, e.g. when you want to run programs from it. You pay for what you provision, which is not necessarily the same as what you use.

EFS is useful when you need to share data among multiple EC2 instances, and can grow and shrink on demand. You pay for what you use.

On the face of it, your use case, as you describe it here, sounds like a good candidate for EFS.