WAN & MAN

According to Wikipedia's entry http://en.wikipedia.org/wiki/Metropolitan_area_network, MANs are "large computer networks usually spanning a campus or a city. They typically use wireless infrastructure or optical fiber connections to link their sites."

According to http://en.wikipedia.org/wiki/Wide_area_network, WAN is "a computer network covering a wide geographical area", meaning wider than a campus or a town.

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A WAN's main ingredient is a router . Mostly it is between two or more sites in different cities or countries . The "cloud" that tie them together is usually a service offered by national telecomunications authorities or nominated access providers. You pay for the link!
A MAN's main ingredients are wireless and fiber ( router or switches ) . As its name implies it is about the METROPOL ( metropolitan = metropolis = big city ) area of a city including its adjacent suburbs . There may be a cloud for the services of which you pay , but since the sites are connected with more than one connection method , you don't have to pay for your private wireless link . Or if you are a local authority ( like municipality ) you don't have to pay for your own fiber cable links and you only put switches instead of routers.

MAN is metropolitan area network, It works in branches of a same company for example in an university different departments can be connected with MAN. It is connected with the private service providers like TV cable.
WAN Wide area network, Global network. Can be accessed from different parts of the world. Internet comes under WAN.