G33 is an Intel integrated board that can support 45 nanometre CPU while the P35 is the first non integrated board to support DDR3 memory. Both boards are powered with Intel chipsets and P35 and G33 are going to be the official names.
Let me refresh your memory P35 supports FSB 1333 CPUs, DDR3 1066 or DDR2 800 memory depending on the implementation and it works with ICH9, ICH9R, ICH9DH Southbridges. The board supports all 45 nanometre CPU's including Quad and dual core.
G33 is an integrated graphic board with DDR3 support. More details soon and we will see a bunch of these boards at Cebit. Cebit will also be full of AMD 690 Graphics chipset and we expect to see few MCP 68, new Nvidia boards.