What is the main difference between LAN's, WAN's and MAN's?

Concept

Computer networks are classified primarily by the physical extent of the area they cover — their geographical scope. This single spatial dimension is the defining property that separates the standard network categories from one another; the labels LAN, MAN and WAN are literally short for Local-, Metropolitan- and Wide-Area Network.

Applying it to LAN, MAN and WAN

Place the three categories on a scale of increasing coverage:

• LAN (Local Area Network): confined to a small area — a single room, building or campus (typically within ~1 km).

• MAN (Metropolitan Area Network): spans a city or a large town, interconnecting many LANs across that metropolitan region.

• WAN (Wide Area Network): spans a country, continent or the whole globe (the Internet is the largest WAN).

Why the other properties are not the defining difference

Data rate, setup cost and the names do correlate with the category, but each is a consequence of the coverage, not the defining basis of classification:

• Data rate varies within each type and overlaps across types (a fast WAN link can exceed a slow LAN), so it cannot uniquely separate them.

• Setup cost follows from how far the network reaches, so it is a downstream effect rather than the criterion itself.

• The names are just labels for the area each one covers, so pointing to the name only restates the coverage difference.

Result: the main, defining difference between LANs, MANs and WANs is their geographical coverage.