The difference in the early and late 2011 MBP 2.2 is how much Vram in the GPU card. Early was 1.0GB (that was the high end) and late is 500MB (that is the lower end). Both are great machines. In Geekbench scores the early 2011 high end scores higher then the 2011 low end. But you can get the early cheaper.
You should be able to see that under details/specifications.
The model number is for a late 2011, and the 512MB (I'm assuming that's for the 6750 since the Intel HD 3000 will only have 384(MB) RAM) also seems to point to a low end Late 2011 model.