Difference in Azure Availability Sets and Scale Sets

Question

Can someone define the difference between the two in the ARM portal. Also what would be the PowerShell if i need to add a new Azure RM VM to a existing AS(Availability Set)? Tha

Answer 1

A scale set is an implicit availability set with five fault domains and five update domains. Scale sets of more than 100 VMs span multiple placement groups, which are equivalent to multiple availability sets.

For more information about placement groups, see Working with large virtual machine scale sets. An availability set of VMs can exist in the same virtual network as a scale set of VMs. A common configuration is to put control node VMs (which often require unique configuration) in an availability set and put data nodes in the scale set.