Call Extensions: It allows you to include your phone number in the Ad text to increase phone calls to your business. Callout Extensions: It shows additional text that appears with your Ad that calls out some value for your customer. Example: 24/7 support, Free Shipping. Callouts are not clickable.
Call extension shows the contact details of your business.
Call Out extension shows the the various offers you have for your potential customers.
This is the subtle difference between Call and Call Out extensions.