Note that it is not wise to travel on a train on either the Business class or the Executive class. Only these two classes allow for reservations.
The executive class is the most expensive and it is air-conditioned. However there are no sleeper berths available like the Indian railways - even on long haul distances.
The business class compartments have only fans and the seats are pretty rigid and that makes it difficult to do long distance journeys on this class. The cost differential between these two classes is only around 5 USD and it would be advised to take the Executive class whenever possible. The rest rooms also are cleaner and better.
We are in our way from Surabaya to Dempasar, Bali by train. We didn't get tickets on the Executive and had no option but to settle for the business. Ts really warm and uncomfortable on this coach. I guess we got pampered by the Exec Class already.
Thank god for small mercies - this coach also has charging sockets. Hence, able to juice up my iPhone.
The first pic is from the Executive class and the second two are on the Business. God speed.