They require different kinds of energies. Specifically, the latter requires negative energy, something we have no evidence exists.
> being in a 'warp bubble' doesn't mean that bubble is traveling at super luminal speeds
Nobody claimed as much. The physically-possible warp bubble lets you slow down time. So a 100,000-year journey would feel, to the ship’s occupants (and its structure and computers, et cetera), like possibly months.
(You also get the capability to transport people and things forward in time without degradation. Or, I believe, to speed up time inside e.g. a production or computational environment.)
that... seems odd to me. without substantial changes in velocity - how does a warp bubble (that's sub-luminal - so relativistic velocities) alter the fabric of space-time so fantastically? It's not moving fast: so where does the time dilation come from?!
I think it’s from shifting momentum?? The paper is far beyond me [1]. But as I understood it, you’re directly modifying space-time with energy instead of using acceleration as a go-between.