According to
https://www.scotrail.co.uk/scotrail-highland-explorer
The ScotRail Highland Explorer carriage has 24 seats as well as 20 cycle spaces. Seats in this carriage will be reserved for those who purchase a 'Highland Explorer ticket'.
If you buy a Highland Explorer ticket, you'll benefit from the following:
A seat in our newly designed Highland Explorer carriage with exterior livery that encapsulates the Scottish scenery
A hospitality offering *
Larger cushioned seats
USB and plug socket charging points
Table maps on board detailing the route, with recommendations on where to walk, cycle and visit
Access to a QR code at each table, providing links to further inspiration on places to visit in Scotland
Those with Standard Class rail tickets will still be able to travel on this service, and they will be seated in the Class 156 carriages, which make up the rest of the train.
* Subject to availability of catering on-board