Question

What is difference between threat and warning​

Answer 1

A warning is giving advance notice of some sort of imminent danger.

A threat is a type of warning where you are planning to cause harm to someone, and you could avoid causing the harm if you wished, but you plan on doing it anyway.

Calling a threat a "warning" does not make it stop being a threat. If it's a situation that is entirely within your control, and you could avoid causing harm to someone, and you tell them that you will not avoid causing harm to them (or heavily imply it), then it's a threat.