These map tiles are based on OpenMapTiles [1], which has a non-commercial side with less-frequent exports of OSM, and a commercial side with frequent updates [2]. The exports can be downloaded as MBTiles (SQLite) databases of vector tiles.
If you're just using tiles, I don't see any difference with Stadia Maps — perhaps price, I don't use OpenMapTiles' commercial services.
Stadia do offer routing using Valhalla, which OpenMapTiles don't offer.
(I have made some small contributions to the open source OpenMapTiles project [result at [3], vector/raster tiles in other projections], but have no connection to the company.)
[1] https://openmaptiles.org/ and [2] https://openmaptiles.com/