What's the overlap between the offline-first and local-first paradigms these days? Both technologically and philosophically?

Not sure there is a formal definition, but here's my current understanding:

In a local-first approach, changes are initially stored locally, but there's an expectation to eventually connect to a server backend to merge these changes, typically within days, weeks, or months. On the other hand, an offline-first approach may not even require a backend, functioning seamlessly regardless of internet connectivity.

These distinctions may blur as sync engines improve, allowing clients to remain offline for increasingly extended periods. Ultimately, the differentiating factor might hinge on whether there's a central authority that enforces migrations or changes.