Why Does My iPad Air 4th Generation Charger Cord Not Work With My iPhone 13?

I need someone to explain this to me as if I were someone's grandmother, lol.

Charger cords that plug into the port on my iPhone 13 will not plug into the port of my iPad Air 4th generation. A huge pain in the a**

Does the new iPhone 15 have the same port as my iPad? Or does the new iPhone 15 have the same port as my iPhone 13?

(I'm trying to figure it out so that I can replace one of my current devices so they will all have the same port).

Thank you,

Linda