I would like to know the difference between "1" and "2".
1. The door is sticking.
2. The door is stuck.
I would say that "The door is sticking" could also be used when it has been the situation for some time.
If my door is difficult to open but can be opened, that may have been the case for quite some time.
"Can someone please come and fix my door. It's sticking. It's been doing it for weeks."
In most cases, unless context shows otherwise, there is no real difference in meaning.