1, with different heights: high-rise buildings are more than 54m, and public buildings are more than 50m. Class II high-rise buildings refer to residential buildings with a height of less than 54 meters and more than 27 meters, and high-rise buildings with a height of less than 50 meters and more than 24 meters.

2. Different uses: A type of high-rise building is often used to build residential buildings, office shopping malls and other civil construction projects. Class II high-rise buildings are often used to build office buildings, shops, hotels, cultural and entertainment venues, bookstores, libraries, exhibition halls, gymnasiums, hotels, houses and so on.

3. Different fire resistance ratings: the fire resistance rating of the first-class high-rise building is Grade I, and that of the second-class high-rise building is Grade II.