Prototype is rendered at 1120 by 640 pixels, with QAA (quinux anti-aliasing) on the PS3 and 2xMSAA (multisample anti-aliasing) on the Xbox 360. The differences between these two solutions for video game "jaggies" are not terribly distinct, apart from a slight blur to the image with QAA; if sufficiently integrated into the game's art style this won't severely impact visual quality (such as is seen in Killzone 2.)
Of course, resolution and aliasing are not really an issue in the PC version of the game, which depending on your set-up can render up to 2560 by 1600 pixels with 4xMSAA.
You will find that the PS3 game's framerate can suffer from significant screen tearing when there's lots of action going on (which is a common occurrence in Prototype). The Xbox 360 game is locked at 30 frames-per-second, and generally runs steadily with minimal screen tearing. Screen tearing is a phenomenon where rendered frames overlap, creating a torn look as two parts of an object fail to line up.
