If you’re looking at a video card upgrade, decoding the model numbers for various graphics chips can be hopelessly confusing. A good resource to help cut through the clutter is this pair of tables put together by Gabriel Torres at Hardware Secrets:
You’ll need to have some basic knowledge of clock speeds, memory interfaces, and other such technical topics, but the charts make it easy to see the difference in different product families.
Ed Bott (@ wordpress.com) 
i thought that the table would gives me idea how to understood the code numbers , it solely comparison table .