Many travellers have become so accustomed to travelling on Eurostar (ES) trains in Italy that they totally overlook lower cost alternatives, such as the Intercity (IC) train and the Regionale ("R") train.
Most of the time, the ES train is the fastest, albeit costliest, option. The ES train is usually also "nicer" than the lower category trains, although this is not an absolute rule.
But there are a couple of examples where the ES train is really a bad deal, compared to the alternatives. One such example is found on the rail line between Rome and Assisi/Perugia, where the two daily ES trains take about the same time as the more frequent "R" trains, yet cost more than double!!! There is even one "R" train which is two minutes FASTER than the ES which departs half an hour later!!!
You do get automatic seat reservations on the ES train, whereas seat reservations are not possible on the "R" train. Yet, this distinction is insignificant on this route, because all trains originate in Rome, so it's not a problem finding a seat if you simply board the "R" train a few minutes prior to scheduled departure.
Both the ES and R trains are air conditioned (most of the time), so there's no difference here.
It should also be noted that the ES trains on the Rome/Perugia route are the oldest in the Trenitalia fleet (indeed the original-issue model), and not even particularly comparable to the fast and sleek contemporary ES convoys between Naples and Milan.
The moral of the tale is always to look at the schedules carefully, because the costliest train is not always the best choice. Sometimes, it's a bad deal.