What is the difference between installing an OTA and dirty flashing a ROM update?

[greydarrah]

I have no idea what goes on behind the scenes of an OTA install, but it seems like it's no different than dirty flashing (not wiping data) a ROM update. I am referring to an update to a ROM that you currently have installed on your phone...not dirty flashing from one ROM to a completely different one. Does anyone know if OTA installs do something special that dirty flashing does not?

 

[2defmouze]

OTA's use patches (.p files) which patch up your entire system to the new version. Custom ROM devs cannot use those, and wouldn't use them anyway, as they need to be very specific about what system they are being applied to.