Just answer me 1 question, /sci/. I'm trying to understand electricity. If a device is 1200 watts AC, which means it draws around 10amps, and another device is 1800 watts which means it draws around 15 amps... what is the key "thing" in the device which "DRAWS" the power? And how is such a device determined? What's the science behind it?

It hurts my head trying to figure it out searching google up and down, I am either finding formulas or applications but not something that answer the question above that is noodling within my mind. Thank you.