What’s the difference between a iPhone and a mac

One is a phone. The other is not. One is small. The other is larger. One runs iOS. The other runs macOS. One has a touch screen. The other uses a hardware keyboard. I could go on but your question is really rather vague. Perhaps if you provided some additional details about what you're trying to find out, someone could give a better answer.

On the iPhone >> Settings User Name appear at Top - click it. Scrolls the Bottom of that screen. How many devices are Listed as Associated with your Apple ID.

The Above is one way to verify what devices are Associated with your Apple ID.

The Other way is to Log Into https://appleid.apple.com/ and see what devices are listed and using your Apple ID

1missippi wrote:

my email security said I have 2 devices a iPhone 12max and a mac . I don’t own a mac and I am confused by this ! Only device I have is my iPhone 12max! Why is it saying I have a mac

Okay, that begins to make more sense. Who is your email provider? If it's Apple, see P.Philips's instructions above. If it's someone else, you'll need to contact them for more information.