The big news about the Early 2015 13″ Retina MacBook Pro is its adoption of the same Force Touch trackpad introduced with the 12″ MacBook. It’s also faster than its predecessor and has improved graphics.
The Mid 2014 Retina MacBooks is essentially a speed bumped version of the Late 2013 model with the base model also boosted from 4 GB of system memory to 8 GB.
The Late 2013 Retina MacBooks have embraced Intel’s latest energy efficient Haswell technology, which provides more processing power per GHz with reduced power consumption. Additionally, the Late 2013 13″ Retina MacBook Pro is a bit thinner and lighter than the Early 2013 model.
Four months after introducing the first 13″ MacBook Pro with Retina Display, Apple introduced a slightly faster version with 2.5 and 2.6 GHz dual-core i5 CPUs.
Four months after introducing the 15″ MacBook Pro with Retina Display, Apple introduced the 13.3″ Retina Display MacBook Pro, making Retina technology available in a smaller, lighter, less expensive package.