The MacBook "Core i7" 1.4 12-Inch (Mid-2017) is a "configure-to-order" version of either the MacBook "Core m3" 1.2 12" (Mid-2017) or the MacBook "Core i5" 1.3 12" (Mid-2017), and is also listed as a distinct model for user convenience. Aside from the processor, this model is identical to its lower-spec counterparts.
The MacBook "Core i7" 1.4 12-Inch (Mid-2017) is powered by a 14-nm 1.4 GHz Intel "Core i7" Kaby Lake processor (I7-7Y75) with two independent "cores" on a single chip and a 4 MB level 3 cache. It includes an "integrated" Intel HD Graphics 615 processor that shares system memory, a default of 8 GB of onboard 1866 MHz LPDDR3 SDRAM (upgradable to 16 GB at purchase, but not later), and either 256 GB or 512 GB of onboard flash storage (depending on whether the base model was the Core m3 or Core i5, respectively).
This is all housed in an exceptionally thin (0.14-0.52 inch), 2.03-pound aluminum case, available in Silver, a darker "Space Gray," Gold, and a pink-hued "Rose Gold" (the Gold option was later updated to a warmer shade and "Rose Gold" was discontinued on October 30, 2018). It features a low-resolution 480p FaceTime webcam, a backlit full-size keyboard with a slim "butterfly mechanism" design, a "Force Touch" trackpad, and a brilliant 12" TFT LED-backlit active-matrix "Retina" display (2304x1440 native resolution at 226 ppi). It provides 10-12 hours of battery life, depending on use.
Compared to its predecessor, it is very similar but features a more advanced processor and graphics, faster storage, the option for twice the RAM, reportedly improved battery life, and a refined keyboard.