Benedict Evans wrote about Android taxonomies.

First, there are actually (at least) six types of ‘Android’ in the market today:

  1. ‘Stock’ Android, as seen on Google’s Nexus devices, complete with Google services (but with tiny unit sales)
  2. ‘Modified’ Android, as seen on phones from Samsung, Sony, LG etc, complete with Google services – generally, these are modifications that no-one especially likes, but which Google explicitly allows
  3. ‘AOSP’ or open Android, as seen in China – essentially these phones are the same as number 2, but with no Google services and apps from the Chinese portals embedded instead. Hence Samsung, Sony etc sell their phones in China without Google services, but few other changes
  4. (or perhaps 3.1) ‘Modified’ Android as seen on Xiaomi phones and those of its followers, which people actually seek out, and which comes without Google services in China and with them elsewhere
    ROMs and third-party implementations of Android that are available for any handset, such as both Xiaomi’s MIUI and Cyanogen (an a16z portfolio company), which may or may not have Google services included or accessible. Again, these contain optimisations and improvements that make people seek them out
  5. Forked Android, such as the Kindle Fire phone: Android heavily modified to produce a different experience, and Google refuses to allow Google services to run on them (other than plain old web search, AKA POWS). Note that Xiaomi and Cyanogen are not forks.

The first two or perhaps three I would describe as ‘closed’ Android and the second three are ‘open’ Android, certainly from the perspective of device manufacturers.

Confusing. But at least know that they are not the same.