Hi all. I'm a graphic designer myself and planning to buy a Mac Book Pro.
I would like to know how much of a difference is there between
"Intel Iris Graphics" and "
Intel Iris Pro Graphics NVIDIA GeForce GT 750M with 2GB GDDR5 memory"? Because I was thinking to buy a 13" MBP which is easier for me to carry around but if the difference is significant then I may consider to get a 15".
Hoping someone could give me some advise.
Many thanks

.
To start, there are three different GPU options for the rMBP lineup.
13" rMBP: Iris HD 5100
15" rMBP: Iris Pro HD 5200
15" rMBP: Iris Pro HD 5200 + gtx 750m
The high end model uses the Iris Pro for basic tasks like web browsing, and the 750m kicks in when there is a heavy workload. Below are 3D benchmarks to compare the GPU performance (notebookcheck.net). I included the HD 5000 from the 2013 MBA just for reference.
gtx 750m: 2512
Iris Pro 5200: 1957
Iris 5100: 1221.5
HD 5000: 1039.5
What this means is that for raw 3D performance, the Iris 5100 is 17.5% faster than the HD 5000, the Iris Pro 5200 is 88% faster than the HD 5000, and the 750m is 141% faster than the HD 5000. In reality, the 750m is more optimized for certain tasks because of the 2GB VRAM (the Iris Pro has a 128MB eDRAM cache, which is still unprecedented for an iGPU, as the Iris 5100 doesn't have an eDRAM cache at all), and may see even better performance in real life scenarios. VRAM allows for faster texture rendering, and it will improve performance for tasks that require it.
Side-note here for CPU performance. CPU performance can be just as important as GPU performance for professional tasks. The quad-core CPU in the 15" rMBP is much more powerful than the dual-core in the 13" rMBP. The eDRAM cache mentioned above is a shared cache with the CPU, so the boost in performance is relative to both the GPU and the CPU. That is a relatively small portion of what drives performance.
Either way, you should be able to do graphics work on the 13" just fine, but the 15" will be much more powerful. If you have the money and are comfortable with a 4.5 pound computer over a 3 pound computer, then the 15" is your best option. Depending on what computer you have right now, I would hold out for new releases in early 2015. If you need a computer now, then the rMBP is great, but I would definitely look at the refurbished store for a better deal.
Matt