New settings for generic esp boards

Hi folks. I’m kinda wondering about the new settings for the generic esp8266 boards that the arduino ide has incorporated in version 1.8. Could any body explain some of the new choices? I’m a noob and I’m getting started again with learning arduino. I set learning aside for a period of time and now I’ve come back to these surprises.
Thank you in advance for your time and effort!
Jerry

I guess it’s a bad question in the wrong place. Have a get day.

Which choices do you have questions about ?

Can we start with the flash selections? There are three, which is used when?
Then maybe lwIP variant, what is it?
It’s just how do you find a guide for the uses? I’ve googled but apparently I’m not asking good questions.

Can we start with the flash selections?

If you mean the Flash Size it allows you to define how much flash memory should be made available for SPIFFS storage

Then maybe lwIP variant, what is it?

lwIP stands for lightweight IP. Mr Google knows more about that than me

There seems to be three choices for erase flash....
Sketch only
Sketch and WiFi settings
All flash contents
Thank you for your time and energy