It is mostly marketing since there is almost no difference for the end user, except the fancy 5G icon on the screen of the phone.
In fact, I am sure that we will never see a decent V2X deployment, at least in Europe, due to the lack of business case.
The number of antennas and base stations that would have to be deployed in combination with the added costs to the vehicles will never be justified over the advantages which is supposedly offering.
In closed environments, e.g. factories, campuses, ets. it will be surely viable but not for a complete deployment in a city or highways.
It will be more interesting to see the developments in the case of remote (IoT) locations in which a lot of devices still work under GSM.
Having said that, C2 having 4G is mooooooooooooore than enough.