Can I differentiate between which tickets are visible online and at the door?

Yes.

During the creation of your ticket types, you tick off the small box 'My guests have to use an access code to buy a ticket on the tickets that should only be visible at the door. Then you go to My events → Manage then on the left-hand side clicking Onsite then Door Sales.

Tick off 'Specify which tickets should be visible on the till' and you can now select which tickets should be visible in the Box Office.

✓ means the ticket will be visible

✗ means the ticket will not be visible

Save your changes by clicking 'Submit'.