Use Trenitalia or Italo for your high speed train travel?

Much the same except Italotren had lower prices. Consider choosing by your schedule

and there are different sites selling train tickets such as raileurope. Should i just buy them at the trentalia and italo sites? or should I shop each of these sites? They are all selling the same 2 high speed train lines right?

You might want to check out trainline.eu.

The site is easy to use, and it includes all Italian train options. The price is the same as if you use the official rail sites.

I've used both extensively and definitely prefer Italo because the customer service is better.

and there are different sites selling train tickets such as raileurope. Should i just buy them at the trentalia and italo sites? or should I shop each of these sites? They are all selling the same 2 high speed train lines right?

I would use Trainline.eu because it sales tickets for both Trenitalia and Italo at no mark up.
Trenitalia does not list Italo and vice versa

There are basically two differences. The first one is that italo is waaaay cheaper. They have generally lower fares (Termini --> Napoli C.le can cost even €9.90), not to mention the fact that more often than not some discount codes are available on their home page and they let you have your ticket at 50% off even on already discounted tickets. On the other hand, Trenitalia has got a significantly higher train frequency.
So to sum up, make a choice basing on your schedule. Then, check on italo for discount codes, and eventually pick the lowest price.
But the most important thing you should do is to get your tickets with at least 30 days in advance, since otherwise prices are likely to be higher. It is extremely rare to have delays higher than 15 mins with both companies. Then, talking about comfort, I prefer Trenitalia because of its slightly better wifi connection. I have no preferences with seats, since they are about the same quality for both companies.

I have never seen the Italo price waaay cheaper for the same fare class. They are priced competitive and one may be a bit cheaper than the other but it just depends. Both trains have similar pricing patterns of deep discount tickets called Super Econ and Econ. There are a limited number of these tickets available and they come with several restrictions. Just think of them as no change, no refund. The SE can be very cheap but are limited and sell out quickly. So pick the ticket that fits your budget and schedule. Little different in the actual equipment used.

I have never seen the Italo price waaay cheaper for the same fare class. They are priced competitive and one may be a bit cheaper than the other but it just depends. Both trains have similar pricing patterns of deep discount tickets called Super Econ and Econ. There are a limited number of these tickets available and they come with several restrictions. Just think of them as no change, no refund. The SE can be very cheap but are limited and sell out quickly. So pick the ticket that fits your budget and schedule. Little different in the actual equipment used.

As I have already said, a trip from Roma Termini to Napoli Centrale could cost around €10 with italo, while Trenitalia won't cost less than €15 (super economy / standard class). If you consider discount codes with italo, there are no terms for comparison.

Let's talk about real numbers. The mentioned trip on October, 24 would cost €7.80 (40% off w/ RIMANI40) with italo and €14.90 with Trenitalia.

I have never seen the Italo price waaay cheaper for the same fare
class. They are priced competitive and one may be a bit cheaper than
the other but it just depends.

Sorry, Andrea, but this is what I've most often seen on Italo versus Trenitalia as well. It's absolutely recommended to check prices/schedules for both but a significant savings for one over the other isn't necessarily a given. Desired departure/journey times for one versus another can also be a factor.

I have found that Italo is at least as cheap as Trenitalia, just with fewer trains. If you purchase ahead of time, Italo seems to have frequent sales (I am now on their email list). I was able to get a $19.90 second class ticket from Venice to Rome in early May.

I have never seen the Italo price waaay cheaper for the same fare
class. They are priced competitive and one may be a bit cheaper than
the other but it just depends.

I'm saying so because I need to travel frequently with high speed trains in my country, and I always find a significant difference. Yesterday I was looking for trains from Florence to Naples, and I found a difference of at least €12 (€63 vs €75-114). My University colleagues claim to pay about 30% less than Trenitalia every time. Once I had to travel to Milan (round trip) and I paid €50 instead of €140 (no discount codes, not planned in advance, a trip was even in comfort class and while Trenitalia still had economy tickets, Italo ran out of low-cost seats).

So maybe you could say that we were extremely lucky, but it was demonstrated that base prices for italo are 12% lower than Trenitalia. We can conclude that special offers play an important role, but generally Italo prices are expected to be lower.

I have found that Italo is at least as cheap as Trenitalia, just with fewer trains. If you purchase ahead of time, Italo seems to have frequent sales (I am now on their email list). I was able to get a $19.90 second class ticket from Venice to Rome in early May.

I totally agree

Thank you for this post really helps as we plan our trip. Hope you don’t mind me asking are both the same in terms of place to hold luggage and how crowded they are? I know I should know this. Do they both leave & arrive from the same station? Thanks for letting me tag on to your question.

Thank you for this post really helps as we plan our trip. Hope you don’t mind me asking are both the same in terms of place to hold luggage and how crowded they are? I know I should know this. Do they both leave & arrive from the same station? Thanks for letting me tag on to your question.

Trenitalia covers both Firenze campo di marte and Firenze Santa Maria Novella, while italo only serves Firenze SMN. Both companies serve either Na C.le and Na Afragola. Extending this to the whole railway network, consider that italo doesn't operate everywhere in Italy (not further than Salerno, then it doesn't operate on the Adriatic coast except for Venice).

I remember having more luggage room on Trenitalia (only on frecciarossa, since frecciargento is awful in terms of luggage space either in first and second class), but even though I use to travel with a very big piece of luggage, I have never had problems with a frecciarossa nor italo.

Attendance is mostly comparable. You are likely to find more passengers traveling in standard (Ti)/smart class(I), rather than business(Ti)/comfort(I) and higher levels. Obviously, trains running at rush hours are more likely to be more attended than trains departing at 6 am

Thank you very much guys for weighing in. We feel more comfortable making a decision now.

on the train from Rome to Naples - do you like one class over another on these trains? Pony up for an upper class or bottom class is fine?

...do you like one class over another on these trains? Pony up for an
upper class or bottom class is fine?

Not sure who you're asking but we've only traveled 2nd class - or bottom class - in Italy. Those train seats are so much more accommodating than coach seats on an airline that we haven't felt the need to spend more for bump up to the next tier. You could do that, of course, if you see a price deal that appeals.