How do you explain to the average user how public key encryption works?

Question

IT education

How do you explain to the average user how public key encryption works?
Do you have any know-how on how to explain to the average user how public key cryptography works, how it differs from using ordinary passwords?
Usually they are interested in why the recipient can simply decrypt, and no one else, although no password is disclosed to the recipient. Accordingly, if someone can - means others. And the second point - they don't understand what does the "keys" have to do with it, how does it differ from "passwords". That is, the very principle of operation causes a lot of misunderstanding.
UPD: Have you ever been asked such questions if you had a chance to communicate with a user about encryption? Many were interested, with whom did you communicate?

Answer 1

Safe with 2 codes: Lock (open) and unlock (closed).
The key from the password differs in length.
A public key is a piece of paper with the seal of a third trusted party that issued it, on which is written 1. The password (i.e. the key itself) 2. Data to whom it was issued 3. Data when it is valid

Answer 2

Regular mailbox.
The open interface is a slot for envelopes or newspapers. Anyone can leave a message to the addressee.
The closed interface is the key to the box, with which the owner opens the box and takes out his correspondence.

Answer 3

I explain it easier :)
The first key can only close it, it is given out to everyone who wants to send a package through it is not clear who.
Only the addressee has the key to open.