"Prime" tickets on regional Italian services

[Watershed]

I'm searching for trains between Brindisi and Bari. Most of the regional services all cost the same - €9.60 for an "Ordinaria" single. However, the 07:44 departure (Regionale 4550) shows as costing more at €11.50 for a "Prime" single. However, it still shows as only having standard class, so "Prime" can't mean first class.

Can anyone explain what this "Prime" ticket is all about and why this particular regional service is more expensive? The only explanation I can think of is that it runs non-stop around commuter times, so perhaps it's deemed a "premium" service? However, I thought that regional tickets were valid on any regional service within the relevant period of validity (usually a few hours, if I'm not mistaken) when you buy a ticket at a ticket machine. Is this not the case here - could one validly use a cheaper "Ordinaria" ticket on that faster service?

If not, does this affect the validity of other passes, such as Interrail and the Trenitalia "Italia in Tour" product, and discounts such as FIP? Is a reservation of some sort required?

I couldn't find any more information about this on the Trenitalia site or elsewhere, so thanks in advance for any advice!

 

[Nunners]

I found this article which explains it:
Press Article (in Italian)

The Regional Prime

In the specific case of Puglia, one of the main innovations in regional transport will be the new Regional Prime service on the Lecce-Bari line. The train will leave from the Salento capital every morning at 7.20 and arrive in Bari Centrale at 8.45, making only one intermediate stop in Brindisi (arrival at 7.43 and departure at 7.44). The return from Bari is scheduled at 17.45 with arrival in Brindisi at 18.46 and in Lecce at 19.10.

Throughout the month of December, regional season-ticket holders along this route will be able to choose to travel on the new Prime train and discover its features. The train in question has a shorter travel time than the Regionali Veloci, which take 1 hour and 41 minutes between Lecce and Bari. All other travellers, starting from 10 December, will be able to purchase single tickets for a journey on the Prime train . The service will be on sale at ticket offices, self-services, travel agencies and on Trenitalia's digital channels

It appears this is an experiment from Trenitalia in this region to have a train in between Regional / Regional Veloce and Frecce, so more expensive and faster than regional tickets but not quite high speed prices. I would have classed it as an intercity but maybe it's not allowed to be if it's technically regional transport.

I have no idea about the interrail implications etc.