There are only four differences between the two 13-inch MacBook Pro models.
MacBook Pro 13-inch 2.5GHz vs. MacBook Pro 13-inch 2.9GHz
1) 2.5GHz Dual-core Intel Core i5 Processor vs. 2.9GHz Dual-core Intel Core i7 Processor
2) 500GB hard drive vs. 750GB hard drive
3) 4GB RAM vs. 8GB RAM
4) $1199 MSRP vs. $1499 MSRP
That's it! For an extra $300, the high-end MacBook 13-inch has a faster processor (i7 instead of i5) running at a higher speed (2.9GHz instead of 2.5Ghz) with 50% more hard drive space and twice as much RAM. Most of that $300 is for the processor because the extra hard drive space and RAM is worth approximately $100. Everything else is the same between the models - graphics card, battery life, etc.
The MacBook Pro 13-inch Retina Display models have only three differences.
MacBook Pro 13-inch 2.5GHz 128GB Retina Display vs. MacBook Pro 13-inch 2.6GHz 256GB Retina Display
1) 128GB SSD vs. 256GB SSD
2) 2.5GHz Dual-core Intel Core i5 vs. 2.6GHz Dual-core Intel Core i5
3) $1499 MSRP vs. $1699 MSRP
Besides the $200 price variation, the only difference between the two models is the size of the SSD and a slight processor speed discrepancy. If you need 256GB then by all means get the high-end model. Otherwise, consider the cheaper version since an extra $200 is only an average deal for an additional 128GB.
The two 15-inch MacBook Pro Retina Display models have five differences.
MacBook Pro 15-inch 2.4GHz Retina Display vs. MacBook Pro 15-inch 2.7GHz Retina Display
1) 2.4GHz Quad-core Intel Core i7 vs. 2.7GHz Quad-core Intel Core i7
2) 256GB SSD vs. 512GB SSD
3) 8GB vs. 16GB
4) NVIDIA GeForce GT 650M with 512MB GDDR5 vs. NVIDIA GeForce GT 650M with 1GB GDDR5
5) $2199 MSRP vs. $2799 MSRP
The main component of that $600 difference is the additional SSD space (which can be quite expensive) and the RAM upgrade.
If you compare the MacBook Pro 15-inch Retina Display to the standard MacBook Pro 15-inch you will notice only a few changes that are somewhat significant.
MacBook Pro 15-inch Retina Display vs. MacBook Pro 15-inch
1) Retina Display vs. 1440 x 900 resolution
2) SSD vs. normal hard drive
3) More RAM in the low end Retina Display than the low-end MBP 15.
4) No Ethernet, SuperDrive, or FireWire 800 in the Retina Display
5) $2199-2799 vs. $1799
When it comes time to decide on your model, try to first narrow your options by choosing a screen size. If it's the 13-inch or 15-inch, I recommend getting the low-end 13-inch or low-end 15-inch. Only get the higher-end option of those two models if it's absolutely necessary. It's much more cost effective to upgrade the RAM and hard drive on your own if you desire a speed boost or run out of space. A memory upgrade for the MacBook Pro is a cheap way to get a significant performance increase from your Mac. Later in this book, I will further discuss memory upgrades.
Consider the 15-inch Retina Display model if you are comfortable with a smaller, but faster hard drive and the absence of a SuperDrive. It's also a great choice for Pro users who want a lighter and more portable option with an eye-popping display. And remember, the Retina Display is unique for MacBook Pro models in that you cannot upgrade the RAM after you purchase it because it's soldered to the motherboard like the MacBook Air.