I rent a room in a building. There are also 9 others who rent other rooms in this building. Just like everyone else who rents a room I only have one key of this building.
With my key I can open the front door of the building. Just like everyone else who rents a room can with their key. However, only I can open the door of my room with my key and the others can't open my room with their keys. I can also not open other peoples rooms with my key. Also, the owner of the house probably has a key that can open all the doors.
So essentially you got the front door which can be unlocked with multiple keys and my room door which can only be unlocked by my key (and the owner of the house).
Is there anything like this in cryptography? Where some messages can be decrypted by multiple people but not just everyone (you have to at least rent a room) while other messages can only be decrypted by 1 or 2 people. Even though everyone only has and uses 1 key.