Use cases and thinking behind the Sparky kernels?

[k410]

If this is already discussed on a web page, I'd be happy with a link to that.

I'm just wondering what customizations/optimizations/patches are involved (and the thinking behind them) in the Sparky current and LTS kernels compared to the stock kernels from Debian Testing.

Also, could someone give a brief comparison of Sparky kernels vs the Liquorix and XanMod ones?