With built-in load balancing for cloud services and virtual machines, we can create highly-available and scalable applications in minutes. But what is Azure Application level routing and load balancing service and how it differs from built-in load balancing for cloud services and virtual machines
I assume you are talking about Azure Application Gateway and Azure Load Balancer.
The primary difference is that AG works at Layer 7, while LB works at Layer 4. AG can be used for HTTP traffic routing, TLS termination, HTTP traffic filtering etc. So you can for example, route requests to the /images path to a different App Service than the rest of the requests.
LB only understands TCP and UDP, and routes packets based on rules to one of the machines in a back-end pool. So for example when a TCP packet arrives on port 80, LB can route it to a random virtual machine in a collection of VMs serving a web app.