what is the term which differentiate the Apple A7 and Apple A8 system on a chips?
Apple A7 The Apple A7 is a 64-bit system on a chip (SoC) designed by Apple Inc. It first appeared in the iPhone 5S, which was introduced on September 10, 2013. Apple states that it is up to twice as fast and has up to twice the graphics power compared to its predecessor, the Apple A6. While not the first 64-bit ARM CPU, it is the first to ship in a consumer smartphone or tablet computer.
Pentalobe security screw The Pentalobe security screw (Apple nomenclature), or pentalobe screw drive, is a five-pointed tamper-resistant system primarily used by Apple in its products. Pentalobe screws have been used by Apple since 2009, when they were first implemented in the 15-inch MacBook Pro. They have since been used on other MacBook Pro, MacBook Air and iPhone models. Apple attracted criticism upon the introduction of the pentalobe screw; it was seen as an attempt to lock individuals out of their devices.