So what is the PHYSICAL difference between an alcino magnet and a ceramic magnet?

Also, what will the difference be audibly?

i like to play Paul Gilbert-y music. Hard rock - shred stuff.
Alnico magnets are made out of rare earth metals: Aluminum, nickel, and cobalt. Hence, AlNiCo.
Ceramic magnets are made out of an iron compound that's fired in a kiln, ceramics-style.

The audible difference depends on the application. With speakers, Alnico speakers tend to have more compression and a more mellow overdrive. In pickups, alnico magnets lend a warmer and less brittle tone. In general, ceramic pickups are only good for high gain. The magnet type in speakers is less crucial.