I am a beginner in camera. I don't know many nouns. What's the difference between a shutter door and a slow door? Thank you.

The difference between shutter doors and slow doors:

"B door" is called slow door, which is a kind of manual control. Open when pressed and close when released. The longer the hand press, the longer the exposure time.

There is also the "T-door", which is also a slow door. Press once to open (whether the hand is loose or open), and press twice to close.

Both of the above are aimed at long exposure.

Except for the above, they are all called blinds. What 1 sec, 1/2 sec, 1/8 sec, etc. Only the shutter speed is slow, not the door.