I noticed that vanilla exists currently as a synonym of stock-android. I know there was a request to merge these tags previously: Merge stock, stock-android, vanilla; define "stock-android"
I'm curious, though, if this is actually correct or if it's confusing. Lie Ryan's answer to that request sums up my personal understanding of "stock" vs "vanilla" rather well:
I think a better definition for "stock" is a manufacturer/carrier-blessed ROMs for a particular device, including upgrades. I prefer to define it this way because some people may not realize that they have an upgraded ROM due to automatic OTA upgrades.
And "vanilla" are ROM which attempts to be as close as possible to original AOSP ROMs (e.g. by removing carrier/manufacturer customization and adding none of their own customization). A vanilla ROM may or may not be produced by a third-party.
In particular, only "Pure Google Experience" phones (e.g. G1, Nexus One, Nexus S), had a ROM that is both stock (comes with the device) and vanilla (no manufacturer/carrier customization).
Now the above has always been my understanding, too, with "stock" referring to "the ROM your device was stocked with" (i.e. off the shelf). However, the tag wiki itself for stock-android seems to be unable to decide what "stock" is either. The summary states:
Broadly, the Android OS that shipped with your device or as updated by your carrier or the manufacturer.
...but then the extended tag wiki says:
This is in contrast to devices with custom operating systems or after-market applications that dramatically change the user interface.
This seems entirely contradictory, since in many cases the OS that ships with your device does dramatically change the user interface.
Can we please find some consistency here? I've personally never attributed "stock" to mean unomodified Android from source so I'm not entirely sure where it got conflated with that definition, but either way this is currently just...confusing.