Provides users with total control over the OS and the services
Does not support autoscaling
VMs are billed even in the Stopped state - Cost for data that is stored on the VM disc

Components: VM Size, Networking, OS Image, Virtual Disk (VHD)
Allows to use custom image that are created and save in Blob storage
Max Nodes : 1

Use cases
Custom software requiring custom configuration
Lift and Shift (Moving On premises services to the Cloud as it is)

Application/Scenarios: Web apps, Databases, Jump box, etc.

Availability Set

Allows to increase the availability of VMs
Fault Domain: Max 20
Update Domain: Max 3 (Region Specific)

Availability Sets - Azure Virtual Machines | Microsoft Learn

Azure Instance Metadata Service (IMDS)

It is an non-routable endpoint that is only accessible from the VM that can be used to retrieve information about the VM
This endpoint can also be used to retrieve token required to access other Azure resources from the VM using Managed Identity

Azure Instance Metadata Service - Azure Virtual Machines | Microsoft Learn

Virtual Machine Scale Set

Allows to creating multiple VMs with the same configuration
The VMs in a scale set are hidden behind an Load Balancer

Users are directed to one of the VMs in the Scale Set
Max Nodes : 1000/ 600 (Depending on Image Selected)

Supports auto scaling feature
Can be performed manually or automatically based on metrics