As many are aware, Italo Treno is the arch rival of state-owned Trenitalia for high-speed rail service in Italy (but only Trenitalia operates non-reserved commuter trains on local and medium-distance routes). Italo Treno competes with Trenitalia on many (but not all) high-speed rail routes within Italy.
There is not much distinction in the quality of service between these two operators on routes where they compete directly. HOWEVER, there ARE at least three major differences:
1. Italo Treno often has lower fares than Trenitalia;
2. Italo Treno's rules and surcharges for reservation changes are more liberal than those of Trenitalia; and
3. Italo Treno has installed high-filtration HEPA filters on its trains, which re-circulate the air every 3 minutes, thereby decreasing the risk of virus contagion.
https://www.italotreno.it/en/the-train/travel-safely
https://www.italotreno.it/en/the-train/hepa-filters
Trenitalia's trains are apparently NOT equipped with HEPA filters. However, Trenitalia is currently studying a PROPOSAL to augment the safety standards of at least some of its high speed trains on several routes by requiring all passengers to have a "green pass" (or its equivalent) which documents their full vaccination status, or having tested negative to Covid-19 no more than 48 hours prior to train boarding. Presumably, American travelers should present their CDC vaccination cards to establish their vaccination status.
https://it.notizie.yahoo.com/sui-treni-frecciarossa-si-potra-salire-solo-con-green-pass-lipotesi-allo-studio-142335798.html