Urban Rail Transit contains two types: Metro and Light Rail. Metro and light rail can built under ground, on ground or elevated above the ground.

The subway type refers to the model of vehicle used in the metro (urban rail transit).In general, there are no uniform standards for metro around the world, with vehicles often tailored to the needs of the subway in one area or country.

According to international standards, urban rail transit trains can be divided into three types: A, B, and C, which correspond to train widths of 3 meters, 2.8 meters, and 2.6 meters respectively.The rail transit line that uses the A-type or B-type train is called the subway, and the train is composed of 5-8 trains. The rail transit line that chooses the C-type train is called the light rail, and the trains of 2~4 sections are used. The model and grouping of the train determine the axle weight and station platform length.

The A-type car is currently the top-level urban rail transit train.It is characterized by a wide carbody with a width of 3 meters.The cost and technical content of B-type and C-type vehicles are smaller than those of A-type vehicles.

The subway（metro） is not limited to this form of operation line in the underground tunnel, but refers to the large-capacity urban rail transit system with high-standard EMUs with a peak hour and one-way transportation capacity of 30,000 to 70,000 people.Subway has diversified operating lines, with a combination of underground, ground and elevated lines.