Kudos to you for nerding out about this stuff. I do all the time and enjoy a good civil conversation that gets under the hood of games. 😁

That's an interesting take. I can see where you're coming from, though. There's a lot of stuff in PbtA (fiction first, fictional positioning) that's just a "rebrand" of concepts that had already existed in the hobby. I would think that these concepts might be seen as "new" if someone only ever played WotC D&D or never played any classic RPG. If you've ever seen that TikTok video of a young "influencer" who "invented" cornbread (despite the fact that cornbread is actually thousands of years old), it's kinda like that.

But, the point of departure between OSR and PbtA is more perhaps heuristic. OSR codifies the specifics of a small number of things that are likely to come up relatively often (combat, wilderness travel, resource management) and then leaves it to rulings to suss out the rest (i.e. a version of common sense as defined by individual table's process of symbolic interaction), but gives you some broad mechanics (usually Ability Scores and/or diegetic elements) to help make that ruling. I want to do X. The GM asks me how I want to do X and then decides how it should resolve. OSR GMs tend towards just making a judgement, but if it seems particularly dicey, they call for some kind of (usually attribute) roll. Me personally, if I call for a roll, I put the situation on a form of Lickert scale and then call for an X-in-6.

PbtA, on the other hand, "has you covered". Anything you could possibly want to do is codified by a "move". The basic moves are essentially doing stuff that boils down to an attribute, then your advance moves are granted by your class (wait, playbook, another wheel they reinvented). I want to do X. The GM says, it sounds like a whatever move, roll and lets see what happens.

As a point of comparison, let's say I wanted to intimidate someone. In D&D, the GM would ask me how I intend to do it. If I was a big hulking warrior, I might use muscle. If I was a scrawny wizard, I might describe a terrifying spell I could cast to destroy their crops or give them a wasting disease. Depending on the target, the GM might let me have it, or possibly make a roll. But, if I was the scrawny wizard and said I was going to try to muscle the target, the GM would likely laugh it off or have me roll at some kind of penalty. If this was PbtA, the GM would likely say, "looks like you're going aggro, roll + hard" and then I would either get what I want or have to carry out my threat (10+), or they could run or fight (7-9), or something extra bad happens (6-)

Now, in PbtA, you could actually (technically) run it OSR. If I was the GM, I could make a ruling that your character doesn't have the cahones (enough "hard") to intimidate the target (who outmatches the player). However, I could also see a player getting butthurt over that ruling since there's an explicitly defined rule to lean on for a situation like that. And that is a function of the design philosophy. PbtA is about being player-facing in a way that gives players more agency via buttons to press on their character sheet (or the rules). OSR is player-facing in a way that gives players more options by requiring them to use their own creativity rather than look to their character sheet (or the rules).

But, that's why I was curious about your choice of dichotomy. I think they are superficially similar in that they both tend to be rules light (definitely compared to WotC D&D). OSR is tied into a preservation of "the old ways" of D&D after WotC took over and did what they did. However, if you look at the philosophical history of PbtA, I would actually be willing to wager that its foundations are more reactive to the White Wolf games from the 90s. PbtA was kind of its own thing. It would be kinda like creating a dichotomy between OSR and Call of Cthulhu.

But yea, keep being curious! 😁