I am honestly getting tired of people complaining about the fact that there is a less ambiguous way to name things. Those projects are more and more converging into saying "AOSP-based" (but that's evolving, interesting how language works!). GrapheneOS always says AOSP-based. The English wikipedia page of LineageOS says AOSP-based. In the past we used to call them custom ROMs, but the naming has evolved.

Of course, it is only relevant when it is relevant.

You can join a discussion about cars, where people talk about their Honda or Opel or Fiat, and when they ask you what you drive, you say "a car". And when they say "no but... which brand", you can go on and explain to them that they don't know how to use language, that "a car" is the common way to talk about those vehicles and that nobody in the world cares about a brand, even though you just witnessed a discussion where those people did care about the brand. Sure, you can do that.

But don't expect to have an enjoyable social interaction this way. And don't tell me "but you started it!": I answered to a comment that was making the article sound ridiculous by proudly conflating the two concepts.