Here's what the help file has to say.
Adds the network to the Trusted list All the network traffic that your computer receives from a Trusted network is filtered and allowed through firewall. However, known attacks and infections are still monitored. You should select this setting only when you are sure that the network is completely safe. | |
Adds the network to the Shared list All the network traffic that your computer receives from a Shared network is filtered. Only shared resources on your computer, such as files, folders, and printers are allowed. You should select this setting if you want the firewall to protect you from all traffic except those that pertain to file and printer sharing. | |
Adds the network to the Protected list A network is in the Protected Trust Level when it has not been classified as Trusted, Shared, or Restricted. You remain protected from known attacks and all unexpected traffic. | |
Adds the network to the Restricted list The devices that are on Restricted network cannot communicate with your computer. However, you can still use the network to browse websites, send email messages, or transmit other communications. |