if your entire kitchen's floor is fill with water then it a הצפה. If if your entire town/neighborhood is fill with water then it a שיטפון. if the entire world is fill with water then it a מבול. there was at most one מבול in the entire history ( depends who you ask ;-] )
I believe מבול is more than a flood. It's a deluge. As the king of France purportedly said, "Apres moi המבול".