Thanks to the PS4′s ability to play games that are being downloaded in the background, you can play your digital titles on any machine.
Forbes - Thanks to the PlayStation 4′s Play As You Download feature, PS4 gamers will be able to play any of their digital games from any system without having to wait hours for a game to download.
“You can visit your friends house you can log into your account and play any game from your digital library, which is good,” said Neil Brown, Sony’s R&D senior team leader, speaking at Develop. “But how useful is that if it takes half a day to download the game you want to play? With Play As You Download you get much quicker access to at least the first section of the game so you can start playing quicker. So this makes a digital library a practical option in the real world.” More
