My understanding is that NATS (a protocol) and NATS streaming were related but separate:

https://github.com/nats-io/nats-site/issues/217

(The issue is from 2017 but illustrates a distinction)

That's right, but I think at least since both are listed on their website as different ways to run it that it should at least be considered a native feature at this point.

All very interesting - this is great!