The accommodation on trains is divided into seven categories, and they are introduced as follows.
Hard Seat (Yingzuo)
It is the cheapest option, and the coaches are usually overcrowded. Though the seats are actually thinly padded, you could hardly sleep on the upright seats. Smoking is permitted here so there is no air-conditioning. The coaches are not clean, and you would never want to visit the toilet. It is usually not advised to buy hard-seat tickets when there are other options available.
Soft Seat (Ruanzuo)
It is one level above the hard seat, and the fare is slightly higher. The seats are relatively cleaner and more comfortable. There will be no over-crowding in soft-seat coaches. In some trains air-conditioning is available. Smoking is not allowed in the coach, but you can smoke at the corridor between cars. Soft seats are ok for several hours’ ride.
Hard sleeper (Yingwo)
It is the basic accommodation for overnight or long-distance train travel. The coach has doorless compartments, in which six bunks are arranged, with three tiers of bunks (upper/middle/lower) on both sides. There is a small difference of price between the bunks, with the upper bunk being the cheapest and the lower bunk the most expensive. A pillow and a sheet are provided for each bunk. There is a small TV hanging in each compartment. Air conditioning is available, and the washroom is tolerably clean. Smoking is not permitted in the coach, but you can smoke at the corridor between cars.
Soft Sleeper (Ruanwo)
It is sort of a luxurious train travel, with the fare almost twice as much as that of the hard sleeper, and sometimes even as much as that of discounted flights. Each compartment is enclosed by a door, and contains four bunks, with two to a side. The bunks are wider and more comfortable, and there is an LCD TV for each bunk. Air-conditioning is available, and the washroom is clean. Smoking is not permitted in the coach, but you can smoke at the corridor between cars. It is advisable to buy soft-sleeper tickets for overnight and long-distance travel.
First Class Seat (Yidengzuo)
They are available in D trains (Dongche). Four seats are arranged for a row. The seats are similar to soft seats, but are wider, more modern and comfortable. Smoking is not allowed.
Second Class Seat (Erdengzuo)
They are available in D trains. Five seats are arranged for a row. It is a level below the first class seats with relatively smaller sitting area, but is still comfortable. Smoking is not allowed.
Luxury Soft Sleeper (Gaobao)
It is the top level sleeper, and the fare is much more expensive than that of soft sleepers. It is only available in a few trains. Each enclosed compartment contains only two clean and comfortable bunks (upper/lower), a western washroom, and sometimes even has a shower cubicle. The ground is carpeted, and other facilities include sofa, LCD TV, table and wardrobe.
You might see also: http://www.chinatravel.com/facts/china-overview/china-transport/china-train-travel/seat-classification-of-china-trains.htm