| Good question! There's a lot of Map<thing>s and it's very unclear how they all fit together without prior experience. OpenStreetMap (OSM) is a community-driven, fully open and usable data library. It has usable data for almost the entire world for everything from cities, roads, houses, parks, country borders, and work. It's a database of everything you need to make map. They also have a website that renders that map, but it's not commercially usable. Mapbox is one of the first companies to take OSM's dataset and commercialize it. Along the way they created a lot of the wildly used mapping libraries, including renders, data formats, and styling tools. Mapbox Studio is one of Mapbox's proprietary tools for working with maps in their ecosystem. Mapbox GL is a suite of renderers, originally entirely open source, developed by Mapbox with the community to render map data (from many different sources). MapLibre GL is a community-driven fork of the Mapbox GL suite, after Mapbox closed the licenses to require payment if you use the latest versions. OpenLayers and Leaflet are both alternative, open source renderers with various levels of capabilities. Interestingly, the creator of Leaflet now works for Mapbox (if my facts are correct and current). |
The commercial players have mostly abandoned this approach, though, in favor of technologies that render on the client. They're more performant (tiles are smaller), and necessary if you want, say, to be able to rotate your map and still have all the labels be upright and not collide, or show/hide individual geographic features dynamically in response to user input, or apply perspective/tilt as you would for a heads-up display in a car, etc.
Mapbox GL was Mapbox building that (as already exists for Google Maps, Apple Maps, etc.). At a very high level, it and Leaflet serve a similar purpose, but are technically very different from one another.
(full disclosure: former Mapbox employee, still a shareholder)