Of course, in the early days before the internet was prevalent, things could really be completely different from store to store or town to town. It's gotten a lot more uniform as people gained access to more and more information about the game, decklists started being published online, and so on.
Even so, historically you can look at the regional championships in different places, in the exact same format, and see really different results. Part of this is separation in time (the meta evolving from one tournament to the next), but part of it is also just different biases in the metagame in each region. There's not actually that many top level MTG players, and often they are testing or sharing tech with one another a lot, so regional groups of players can have kind of an outsized influence on what their local meta looks like.
A lot of my reading on this though has been focused on really high-level play, which is by nature kind of its own unified metagame. A pro tour is made up mostly of players who are traveling to be there, after all.
The most salient meta differences these days tend to be online vs paper, for a couple reasons. Online reward structures like arena’s ladder and MTGO leagues incentivize aggro or linear combo decks that can win as quickly as possible to play more matches whereas paper play incentivizes slower decks because it’s possible to win 1-0-1 by using a majority of the clock. MTGO and Arena also don’t have the same tournament rules as paper, making playing decks that rely on infinite loops onerous. I firmly believe Aluren has long been underrepresented in the legacy meta simply because it’s profoundly annoying to win with on MTGO; you can see that it’s much more prevalent in the idiosyncratic Japanese Legacy meta which tends to be less affected by MTGO.
Of course, there’s also card availability concerns; the cost of cardboard shapes what people play in paper, especially in older formats, and some Legacy playable cards continue to be unavailable on MTGO for licensing reasons, including Triumph of St. Katherine, a key card in the deck that just won the North American Legacy Championship.
