That's the same screen tech employed in the Galaxy S2, and differs from the display on the Galaxy Nexus because it's not a pentile display. Pentile displays use a red-green-blue-green subpixel layout, and you get fewer sub-pixels in total than you do with a classic RBG arrangement. It's a display tech that's come under fire for not being as sharp than other display types.
The bottom line is that the S3's screen may be a bit crisper than the Nexus', while being the same size and resolution, and still offering the deep blacks and bright colours that an AMOLED screen affords.
Sounds alright to me, though we've had our fingers burned with S3 rumours in the past -- word emerged a while back that Samsung's next flagship phone would have a 1080p resolution screen, but now it doesn't look like that's the case. All we know for sure is that we'll see it in the first half of this year.
For a comprehensive roundup of what we've heard regarding the S3, check out our complete guide. And let me know what you're hoping to see from Samsung's next phone in the comments below, or over on our Facebook wall.