> . A general thread of execution is just a sequence of continuations executed one after another.

you're using a definition of "thread" that is quite abstract and not at all what is generally meant by most people when discussing these things

> multiple lightweight threads map on an heavier weight thread like in Node

describing Node as implementing M:N threading, while correct in an abstract sense, is not really useful or again, how most people would describe it.

> A specialized async/await runtime is a bit different from the typical M:N runtime... but conceptually there isn't much difference.

sure, conceptually, but again, you're using definitions in a very idiosyncratic and abstract manner. Which is your right, but it's not very persuasive and it's out of touch with how most people talk about these things.