This is great and reminds me of the orthogonal discussion of what is self hosting!
I find this to be true for words in general. Well. A lot of them, anyway. Their meaning depend heavily on context.
These overloaded terms are harder to explain, due to the person (who I am explaining to) having misconceptions about what the term is.
Like, when I explain what ‘server’ is, I always have to explain that the physical computer called server is different from what I’m trying to explain. :-( When I (forget and) don’t, everything gets mixed up and both people lose track of the conversation…
Not only that, but “instance” and “host” get a bit overloaded too, and can end up having fluid meanings within a conversation.