IC and Freccia are different service, but same company. Trenitalia.

As Perche explained tickets purchased at the counters or newsagents need validations since they have no time limit from the moment you buy it.
Validation proves the exact moment it starts its life.

All high speed trains (either Trenitalia and Italotreno) don't need validation as they are segment-specific.
So they just work for the booked train on a given reserved seat.
Pretty much like flights.

What inspector needs is just the PNR or reservation #, not even the actual ticket, though is always a good idea to have it as backup.