In this question :
What is the difference between a battery and a charged capacitor?
It is said that the battery does not have a charge separation on its electrodes and only the chemical reaction generates voltage. But in the comment, it is said again that there's charge separation on the electrodes thus producing the electric field and voltage.
so at the end there's a small charge separation in the battery so how a battery differs from a capacitor? can we say it is due to chemical reaction there's charge separation? When the circuit is closed, there's drop in electric field, why the chemical reaction does not maintain the charge separation as in the open circuit?