Question: what is the term which differentiate the Apple A7 and Apple A8 system on a chips?

Context paragraphs:
IPad Air: The iPad Air is the first-generation iPad Air tablet computer designed, developed and marketed by Apple Inc. It was announced on October 22, 2013, and was released on November 1, 2013.  The iPad Air features a thinner design with similarities to the contemporary iPad Mini 2, along with the same 64-bit Apple A7 processor with M7 coprocessor.  It was then discontinued with the launch of a 9.7 inch iPad Pro on March 21, 2016.

Apple A8X: The Apple A8X is a 64-bit ARM-based system on a chip (SoC) designed by Apple Inc. and manufactured by TSMC.  It first appeared in the iPad Air 2, which was announced on October 16, 2014.  It is a variant of the A8 inside the iPhone 6 family of smartphones and Apple states that it has 40% more CPU performance and 2.5 times the graphics performance of its predecessor, the Apple A7.

Apple chips: Apple chips are chips or crisps that are prepared using apple.  Apple chips may be fried, deep fried, vacuum fried, dehydrated or baked.  Apple chips may have a dense and crispy texture, or may be puffed, yet still crispy.  Microwave vacuum-drying may be used to prepare apple chips with a puffy and crispy texture.  They may be seasoned with cinnamon and sweetened with confectioners sugar.  Apple chips may be consumed as a snack food, and may be accompanied with various dips and other foods.  Apple chips are mass-produced in the United States.

Apple A8: The Apple A8 is a 64-bit ARM-based system on a chip (SoC) designed by Apple Inc. It first appeared in the iPhone 6 and iPhone 6 Plus, which were introduced on September 9, 2014.  Apple states that it has 25% more CPU performance and 50% more graphics performance while drawing only 50% of the power of its predecessor, the Apple A7.

Apple Silentype: The Apple Silentype is Apple Inc.'s first printer, announced in 1979 and released in March 1980 for US$599, shortly after the Apple II Plus.  The Silentype's firmware was written by Andy Hertzfeld, who later worked on the Apple Macintosh.  The Silentype is a thermal printer, which uses a special paper and provides 80-column output.  It was also compatible with the Apple III.  The Silentype printer needs its own specially designed interface card, or an Apple III with the built-in Silentype port.  It is mechanically similar to the 3M Whisper Writer 1000 and identical to Trendcom's Model 200 and the Axonix ThinPrint 80 (the first, thermal version, not the later DMP model), except for the Apple logo in the lower left corner of the front cover, but the internal digital board was completely redesigned by Apple, removing the relatively expensive microprocessor and memory chips, relying on software in the Apple II instead.  It was succeeded by the Apple Dot Matrix Printer, released in October 1982 for US$699.

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.

Applesoft BASIC: Applesoft BASIC is a dialect of Microsoft BASIC, developed by Marc McDonald and Ric Weiland, supplied with the Apple II series of computers.  It supersedes Integer BASIC and is the BASIC in ROM in all Apple II series computers after the original Apple II model.  It is also referred to as FP BASIC (from "floating point") because of the Disk Operating System (DOS) command used to invoke it, instead of INT for Integer BASIC.  Applesoft BASIC was supplied by Microsoft and its name is derived from the names of both Apple and Microsoft.  Apple employees, including Randy Wigginton, adapted Microsoft's interpreter for the Apple II and added several features.  The first version of Applesoft was released in 1977 only on cassette tape and lacked proper support for high-resolution graphics.  Applesoft II, which was made available on cassette and disk and in the ROM of the Apple II Plus and subsequent models, was released in 1978.  It is this latter version, which has some syntax differences from the first as well as support for the Apple II high-resolution graphics modes, that most people mean by the term "Applesoft".

List of mergers and acquisitions by Apple: Apple Inc. is an American multinational corporation that designs and manufactures consumer electronics and software products.  It was established in Cupertino, California, on April 1, 1976, by Steve Jobs, Steve Wozniak, and Ronald Wayne, and was incorporated on January 3, 1977.  The company's hardware products include the Macintosh line of personal computers, the iPod line of portable media players, the iPad line of tablets, the iPhone line of smartphones, the Apple TV line of digital media players, and the Apple Watch line of smartwatches.  Apple's software products include the OS X operating system, the iOS mobile operating system, the tvOS operating system, the watchOS operating system, the iTunes media browser, and the iLife suite of multimedia and creativity software.  As of 2017 , Apple is publicly known to have acquired 70 companies.  The actual number of acquisitions is possibly larger as Apple does not reveal the majority of its acquisitions unless discovered by journals.  Apple has also purchased stakes in two companies, as well as made two divestments. Apple has not released the financial details for the majority of its mergers and acquisitions.

A8 (Croatia): The A8 motorway (Croatian: "Autocesta A8" ) is a 64.0 km toll motorway in Croatia.  It connects the A7 motorway near Rijeka with the road network in the Istrian peninsula via the Učka Tunnel.  The road terminates at the Kanfanar interchange with the A9 motorway, which with the A8 motorway forms the Istrian Y road system.  The motorway's national significance is reflected in its positive economic impact on the cities and towns it connects, as well as its importance to tourism in Croatia.  The importance of the motorway for tourism is particularly high during the summer tourist season, when its traffic volume increases by about 65%.

Apple A9: The Apple A9 is a 64-bit ARM-based system-on-chip (SoC), designed by Apple Inc.  Manufactured for Apple by both TSMC and Samsung, it first appeared in the iPhone 6S and 6S Plus which were introduced on September 9, 2015.  Apple stated that it had 70% more CPU performance and 90% more graphics performance compared to its predecessor, the Apple A8, and was one of the most powerful and energy-efficient mobile chips on the market then along with the Samsung Exynos 8890 and Qualcomm Snapdragon 820.

Supporting paragraphs: Apple A8 Apple A7
Answer: ARM