In our efforts to improve the World of Tanks experience from the very beginning, we have introduced a new World of Tanks “mini client”, to be available within the next couple of weeks.
The mini client offers you a smaller download size, that enables you to start playing in less time by giving you faster access to Tier I-II vehicles and random battles. This is first and foremost a great option for new players who would have to begin from Tier I regardless, or secondarily as a way to check if World of Tanks runs suitably on your PC and internet connection without having to wait for the entire game to download.
This can be a temporary limitation -- again, the mini client can continue to download the rest of the game and become the full client. In other words, once everything is downloaded, every feature of World of Tanks is available!