What factors differentiate network infrastructures from each other?

Area covered, number of users, services offered, and area of responsibility — and the two most common types are LAN and WAN.

Network infrastructures vary greatly in terms of:

• Size of the area covered
• Number of users connected
• Number and types of services available
• Area of responsibility

The two most common types of network infrastructures are LAN (Local Area Network) and WAN (Wide Area Network).

Go deeper:

• LANs and WANs (Cisco Press) — states the exact four differentiating factors (area covered, number of users, services, area of responsibility) and that LAN/WAN are the most common types.
• Local area network (Wikipedia) — LAN scope and ownership.
• Wide area network (Wikipedia) — WAN geographic scale and leased-link contrast with LAN.