AWS Elastic Load Balancing (ELB) vs Fly: What are the differences?

Developers describe AWS Elastic Load Balancing (ELB) as "Automatically distribute your incoming application traffic across multiple Amazon EC2 instances". With Elastic Load Balancing, you can add and remove EC2 instances as your needs change without disrupting the overall flow of information. If one EC2 instance fails, Elastic Load Balancing automatically reroutes the traffic to the remaining running EC2 instances. If the failed EC2 instance is restored, Elastic Load Balancing restores the traffic to that instance. Elastic Load Balancing offers clients a single point of contact, and it can also serve as the first line of defense against attacks on your network. You can offload the work of encryption and decryption to Elastic Load Balancing, so your servers can focus on their main task. On the other hand, Fly is detailed as "A global load balancer with middleware". Deploy apps through our global load balancer with minimal shenanigans. All Fly-enabled applications get free SSL certificates, accept traffic through our global network of datacenters, and encrypt all traffic from visitors through to application servers.

AWS Elastic Load Balancing (ELB) and Fly can be primarily classified as "Load Balancer / Reverse Proxy" tools.