op amp vs zener diode

Two completely different things -- you're way off. A zener diode is a diode made to have a certain voltage across it when reverse-biased with a current source (within a certain range). When forward-conducting, it acts pretty much like a regular diode. That's all it does.

An op amp is an integrated circuit composed of dozens of transistors whose output function is to amplify the difference between its two inputs.

It might help to go to the library and pick up a book on basic electronics.

I'm trying to assume you have a real question. Are you referring to using an op amp as a reference voltage source, and comparing that with a zener? Or what? Sadly, your question as it's originally phrased is "not even wrong". Sorry.

Chris

I'm thinking he/she is mistaking an op-amp for an IC regulator.

Tom