The local makes every stop between cities, the express makes only a few stops, and the Intercity makes none.
Reservations are necessary for a first class seat.
Most of the larger trains have both smoking and non-smoking compartments, and some have a family car for families traveling with children. Bringing food and water is a good idea. There are spartan but functional restrooms on the trains. Luggage remains with the passengers unless it is something large like a bicycle, and passengers should watch their luggage. On long trips or night trains, it is a good idea to sit in compartments with more than one person in them since theft is not uncommon.