The difference between OS Disk, Data Disk and Temporary Disk.

WHAT IS A DISK IN AZURE?
In azure, a disk is a place to store an operating system, applications and data.

There are three main disk in Azure:
1) Operating System disk
2) Data disk
3) Temporary disk.

Operating System disk
a) The OS disk is the disk that houses the operating system.
b) That OS disk has a pre-installed OS, which was selected when the
VM was created.
c) This disk contains the boot volume (This is where OS stores it
system files)
d) Os disk is persistent.

Data disk
a) A data disk is a managed disk that's attached to a virtual
machine to store application data, or other data you need to
keep.
b) Data disks are registered as SCSI (Small Computer System
Interface) drives and are labeled with a letter that you choose.
c) The size of the virtual machine determines how many data disks
you can attach to it.
d) Data disk is persistent.
e) Generally, you should use the data disk to store your
applications and data, instead of storing them on OS disks.

Temporary disk
a) The temporary disk provides short-term storage for applications
and processes, and is intended to only store data such as page
files, swap files etc.
b) Most VMs contain a temporary disk, which is not a managed disk. c) Data on the temporary disk may be lost during a maintenance,
when you redeploy a VM, or when you stop the VM.