It's all about the screen, no? Remember, whatever options you select with a Retina are it, there is no later upgrading the SSD, memory, or processor. The 2.7 GHZ is the speediest one, to have that, upgrade the memory to 16 GB and increase the SSD size to 768 GB, all of a sudden you are talking $3749 with no optical drive - add another $79 for that. Pricey.
The MB Pro maxed out with 2.7 GHZ processor, but 8GB of memory and with the standard 750 GB HDD is $1200 less.