So far we are aware of a few different Haswell graphics cores. The main distinction is that the G3 is more powerful and faster, while and GT2 is smaller, less powerful and obviously more efficient.
The fastest of all of them for notebook computing is GT3 with cache memory on board that ends up with Intel HD Graphics 5200 branding. This part goes into high performance notebooks and we can imagine that this core will find its place in quad core Haswell processors.
The GT3 for Ultrabooks will end up branded as Intel HD Graphics 5200 for the faster one and Intel HD Graphics 5100 for a somewhat slower version. We don’t know the clocks or the actual specification for the 5000 series, just brands. GT3 for Ultrabooks doesn’t come with on package memory, probably due to a limited space on this dual core.
Intel GT2 HD graphics target high end notebook computers at high clocks and they end up with Intel HD Graphics 4600 branding. Intel GT2 HD graphics for Ultrabooks will end up branded as Intel HD Graphics 4400 for the faster one and Intel HD Graphics 4200 for the slowest of the GT2s for the mobile.
Intel also claims that same graphics numbering system applies across client and server products.