Help to understand the difference between AA and AB coin [solved]

Hello! Help me, please, identify the difference between the 1 Penny - Elizabeth II 4th portrait 2003 AA and 1 Penny - Elizabeth II 4th portrait 2003 AB. Thank you in advance for your help.

It's the die number/designation. In this example (https://en.numista.com/catalogue/pieces5728.html) it is under the church right hand side.
This question comes up quite often someone should write something in the comment field of those coins.

For the next time please be a bit more specific the best would be a link to the coin in question when you have a question or at least let us know the country

Thank you very much for your answer.Yes,that is the coin I was asking about.

Hello.
http://monnaiesetvarietes.esy.es/
Michel