In fact, not every stations have Platform Screen Doors (PSD) and Automatic Platform Gate (APG).
For PSD, only the MTR which is air - conditioned, Tsim Sha Tsui East Sta. and the whole West Rail has installed PSD.
For APG. only Sunny Bay station has installed.
The difference between not installed and installed is (PSD):
1. The wind in the platform has decrease a lot.
2. The temperature in the station has lower.
3. (Especially in Prince Edward Station) Less smell.
4. Increase the tidiness of the platform.