We have different series of instance in Azure for Compute resources as in pricing tiers for VMs cluster, databases .Mainly for VMs we have High-performance compute ,general Purpose,Compute optimized, Memory optimized etc and it has A , B, D , E series.For more details :https://www.nakivo.com/blog/comparison-of-microsoft-azure-instance-types/
Hi Roshan,
Azure provides multiple services for different purpose like Storage, compute, data and analytics, ai. For each of the service, it provides different subtypes and instance type. Better to refer to MS Docs based on syb type for more info