Postcard is a visual, card-based layout with 7 display options per item/service — ideal for proposals.
Final is a detailed list view where each item expands to show dates, times, options, and descriptions — better for confirmed itineraries.
New itineraries default to Postcard. You can change the layout to Final on the itinerary Setup page or on the Preview page (Preview > options menu (top right) > Customise display).