If you use AWS, you have two load-balancing options: ELB and ALB. And while choice is always a good thing, the ELB vs. ALB debate can be intimidating.
The Elastic Load Balancer (ELB) was released by AWS in the spring of 2009. An ELB is a software-based load balancer which can be set up and configured in front of a collection of AWS Elastic Compute (EC2) instances. The load balancer serves as a single entry point for consumers of the EC2 instances and distributes incoming traffic across all machines available to receive requests.
In addition to providing a single point of entry, the ELB also performs a vital role in improving the fault tolerance of the services which it fronts. The ELB regularly conducts a health check of all instances which have been registered with it, and only routes traffic to those machines which respond as active and healthy to the health check.
In 2016, AWS augmented its Classic ELB offering with an Application Load Balancer (ALB). The Classic ELB and the ALB share commonalities in function, but the ALB has been specialized to provide users with enhanced capabilities.
Courtesy : https://www.sumologic.com/blog/amazon-web-services/aws-elb-alb/