[apendleton]

If you never change what you display, that might well end up being true, but if changing display state (you want to highlight or shade or hide a feature, for example) that would likely require downloading whole new tiles for raster but could be a pretty trivial mutation of the current local state that doesn't require a full re-render from scratch. You probably also don't need to download as much on zoom; there are tiles for different zoom levels with vector tiles because tiles get really large when zoomed way out otherwise, mostly full of features or detail you can't see or wouldn't show, but you might not need as many, and can overzoom a given tile and have it still look nice with relatively few artifacts. All of which is to say: it depends.

[m4rtink]

To some degree its possible to combine bitmap tiles and client side lightweight vector overlay. If you want to work with ortofoto (basically satellite/airplane captured imagery) then you basically have to do it that way.