The thing which makes a metaphor is:
The comparison which it does of two distinct things.
A metaphor has to do with the direct comparison of things and this is used in literary terms as the attribution of one qualrity to a person or thing.
For example, a speaker can say, "John is a lion" and this is a direct comparison to show that John is either strong, fierce as a lion and this is different from a simile which makes use of like or as.
Read more about metaphor here:
https://brainly.com/question/9418370