Doubts about Energy Shield

Guys, I'm new with a build with ES

and the question is:

what's the difference between Energy shield recharge and Energy shield Regeneration?

and what is Energy shield recharge occurrence modifier?

Recharge is a mechanic that occurs when the character's life and energy shield has not changed (typically means take some damage) in the last (base of) 2 seconds. This also means it can be interrupted if life/es changes while recharging.

The one exception to this is spending energy shield through Eldritch Battery, and Wicked Ward will make recharge uninterruptable for a short period after starting

Recharge occurs at a base rate of 20% of maximum energy shield per second.

Regeneration is just a passive, constant recovery of energy shield.

Recharge is typically very powerful but a harder to let occur and regeneration is typically weaker but consistent

https://pathofexile.gamepedia.com/Energy_shield

Regen for ES works the same as for life. Recharge is similar except it's situational.

Regen happens continuously no matter what you are doing. Recharge only works when you have not taken damage in the last two seconds.

For example:
Recharge is 20% of ES per second.
Let's say you had 20% regen for life.

The 20% life will work constantly.
The 20% recharge will work ONLY if you haven't taken damage in the last two seconds.

At this point, both would regen/recharge life/ES at 20% per second. If you had 1000 life and 1000 ES, then you would regen/recharge 200 life and 200 ES per second.

Now if you take damage, then ES recharge would stop, but life regen would continue until you reached full health.

There are lots of ways to change all this, but that's how it works with nothing else affecting it.