The discussion at What is the difference between WGS84 and EPSG4326? shows that 4326 is just the EPSG identifier of WGS84..
Wikipedia entries for Google Maps and OpenStreetMap shows that they both use WGS 84.
http://wiki.openstreetmap.org/wiki/EPSG:3857 states that
EPSG:3857 is a Spherical Mercator projection coordinate system popularized by web services such as Google and later OpenStreetMap.
Leaflet's help states:
EPSG3857 The most common CRS for online maps, used by almost all free and commercial tile providers. Uses Spherical Mercator projection. Set in by default in Map's crs option.|
EPSG4326 A common CRS among GIS enthusiasts. Uses simple Equirectangular projection.
This is confusing - it seems that Google Maps and OpenStreetMap use EPSG3857 but they use WGS84 which 'is' EPSG4326. Something can't be right here, most likely my understanding.
Could someone help me understand?