The most popular intercity transport in Thailand is buses. Trains are not as popular because of the small number of departures. The cost of bus tickets for equal distances is often lower than for the train, travel time is shorter, and the trip itself is more comfortable. Still, in some cases, it is better to use the railroad. Thailand has its classification of trains, by which you can determine the characteristics of a particular train (ticket price, comfort, travel time, number of stops, etc.). In turn, each train has different types of cars. Since I am from Germany and always used to watch the timetable https://www.dbauskunft.com/de/ this skill came in handy in Thailand.