How big is the world of warcraft map compared to the runescape map?

I would appreciate answers that compared, like how many entire runescape maps(with membership) could fit into all of world of warcraft, or how many varrocks could fit into a WoW main city, etc.
two more things, do you walk in WoW as fast as in runescape? how big is a WoW main city compared to a big city in runescape?