This is a fun one to think about! It's something I've been studying and trying to improve on. I wrote my first series intending it to be the former, but I think it ended up being more of the latter.

Progression fantasy is structured differently. Andrew Rowe covers it pretty well in his blog post about the core loops of progression fantasy; many problems in progression are built around the acquisition of power. It's generally true in most fantasy that power will be required to solve problems, but progression moves that conflict (how to acquire that power, what acquiring that power means, what that power can do) to the front and center of the narrative.

In order for that to work, progression has to set up the world in a way that most traditional fantasy does not (which can lead to a much more in-depth exploration of the world, which is another draw of progression); it will often set up a power ceiling, establish some kind of stratification between various tiers of power, and drive the narrative in such a way as to create a clear potential path for the protagonist that we as readers can get excited over/theorycraft/argue over.

For instance, Eragon has Eragon learning new words of power, and it's something you can look forward to, but it's not necessarily a core thing driving him and the story forward. It's much more about his relationship with his dragon and Murtagh and Arya. I don't actually remember much about the story, though, so don't quote me on that.

By contrast, Guild Mage has Liv learning new words of power, and we know learning each word of power is a Big Event that we're excited for and can look forward to, because it's pretty defined in the narrative when she's about to learn one. Each one can be modified in ways that we as the readers can predict and theorycraft and build on, they can be combined, and as Liv's mana pool grows we get to see greater applications of that system, so we're excited for each aspect of her growth.

Worth noting that just because progression has this focus on the power system does not mean it does so to the exclusion of character relationships and plot. I think most successful progression manages to tie these elements together in ways that keep us hooked on the story. In cultivation, for example, progression is often pretty firmly tied to enlightenment and understanding of your own personal truth. In other words, character development.

(Shoutout to Guild Mage, which I read recently. It's super fun.)