I believe, but haven't bothered to profile, that they're lighter. You can also pre-"render" the vector tiles and store them in eg S3. All styling is done in-browser, which means you can do neat things like swap out the styles client-side for dark mode without needing to reload map tiles.
The primary standard for vector tiles is Mapbox Vector Tiles (it's an open standard), which is really just a sqlite database following a particular schema.
My own personal experience developing against both png and vector tiles over the past few months is that vector tiles are better in just about every way for the kinds of things you use maps for in apps. I expect that some dataviz applications, though, would be better served by raster tiles, since you'd end up generating a raster overlay anyways.
The primary standard for vector tiles is Mapbox Vector Tiles (it's an open standard), which is really just a sqlite database following a particular schema.
My own personal experience developing against both png and vector tiles over the past few months is that vector tiles are better in just about every way for the kinds of things you use maps for in apps. I expect that some dataviz applications, though, would be better served by raster tiles, since you'd end up generating a raster overlay anyways.