Queries regarding Private Endpoint & Private Link

Hi AshishGupta1 

So 

1. Yes all the traffic which is between Azure services travels over Microsoft backbone network.
   This is documented here

      Yes, any traffic between data centers, within Microsoft Azure or between Microsoft services such as Virtual Machines, Microsoft 365, XBox, SQL DBs, Storage, and virtual networks are routed within our global network and never over the public Internet, to ensure optimal performance and integrity.

2. Service endpoints provide an extra layer of isolation and security , as per Microsoft Docs :

    Network connections can only be initiated by clients connecting to the private endpoint. Service       providers don't have routing configuration to create connections into service consumers. Connections can only be established in a single direction.

To understand the private endpoints in better way I would recommend to read more about Private Link Service as well.