I am booking a train from Venice to Florence. I see there are two different train companies, Italo and TrenItalia. There is a significant price difference between the two companies. Is there any reason to avoid Italo, as there is a significant savings?

" Is there any reason to avoid Italo"

No. Assuming you've checked that you're comparing like for like (finding the very lowest available fare on Trenitalia isn't always as easy as with Italotreno), the two offer virtually identical speed, facilities and routing.

At Milan and Rome, though, Italotreno uses a different station from Trenitalia - and most tourists find the Italotreno station less convenient. Otherwise, just put the fare difference down to the joys of competition

>>>There is a significant price difference between the two companies.<<<

Usually there isn't much difference. What sites are you using to check fares? Often Trenitalia has more discount tickets as it offers many more trains. The cheapest fare I've seen on Italo between major cities is 20€. Trenitalia's cheapest is 9€.

If you are on the island of Venice and going to the center of Florence, make sure you book from Venice Santa Lucia to Florence Santa Maria Novella. On the Trenitalia site, that would be Venezia S.Lucia to Firenze or Florence SM Novella.

I took the Italo from Venice SL to Florence SMN a few weeks ago. It was fine, no noticeable difference from the trains on Trenitalia at all. But I waited too long to buy the ticket in Venice, and the cheapest fare was sold out, so had to buy the 31 E ticket. Book or buy early!