so you want to know what are the most common differences between a private network and a public network.

fist, you must understand what is a private network and what is a public network.

public network = a network that is open to anyone to access to. the ONLY public network i know of as of today is called the INTERNET. you are using a public network to read this post here. also, you can called the internet a WAN (Wide Area Network)

private network = a private network, is the opposite of the public network. an analogy i can use is a private party and a public party. a public party means anyone can go there, much like a dance club. but if you want to go to a private party, you have to have an invitation to go in. the invitation is your permission to go in the private party. to access a private network, you must have the permissions to access that network. most likely, your computer is connected to a private network which access the internet. a private network is a usually a small network at home. some large offices may have a very large private network. a private network is a LAN (Local Area Network)

did you understand?