The nations available at release are the original three nations from the game’s PC launch: the United States, Germany, and the Soviet Union. There are five distinct vehicle classes that are playable for each country: heavy tanks, medium tanks, light tanks, tank destroyers, and self-propelled guns (SPGs). 

The announcement on the official WoT website also states that players will be able to receive a ‘Beta Exclusive Tank’:

Details were also released about an iconic premium vehicle only available to Playstation Plus subscribers. Wargaming wrote:

If you play on the PS4 and are keen to get into World of Tanks, then the timing could literally not be better, so take advantage of all these release deals before the end of January.

Watch the WoT PS4 launch trailer here:

World of Tanks released on PS4   World of Tanks - 1