Serviceable products require an appointment when booked via the order form. Good examples of serviceable products include photography, videos, Matterport/iGuide, etc.
Non-Serviceable products do not require an appointment when booked via the order form. Examples of non-serviceable products might include virtual staging, blue sky replacement, virtual twilights, etc. These would be services that happen after the appointment during the editing phase and do not require an appointment duration.
Indicating that the product is serviceable will allow you to set a duration and provide additional scheduling options like twilight preferences for example.