VPN (Virtual Private Network) is a technology that can safely connect to a private network through a public network, and “over the wall” is a way to access restricted websites or services by using network proxies or other technologies. Here are their respective pros and cons:

Advantages of VPNs:

High security: The encryption function provided by the VPN can protect the user’s privacy and data from being stolen or monitored.
Privacy protection: VPN can hide the user’s real IP address and protect the user’s online privacy.
Access Restricted Content: A VPN can unblock geo-location restrictions and access foreign websites and services.
Unlimited bandwidth: VPN is not restricted by geographical location and can enjoy high-speed network connections.
Disadvantages of VPNs:

Need to pay: VPN services usually require users to pay, and some services are more expensive.
Slow connection speed: VPN services need to go through processes such as encryption and decryption, which will result in a certain loss of connection speed.
Unreliable service providers exist: Some VPN service providers may steal users’ information or engage in other bad behavior.
Need to download and install the client: Using a VPN requires users to download and install the client, which may lead to certain security risks.
Advantages over the wall:

Access restricted content: Over the wall can remove geographical restrictions and access foreign websites and services.
Free: Some firewall circumvention services are free and do not require any payment.
Ease of use: Some circumvention services require no download and installation, just use a browser plug-in or visit a specific website.
Disadvantages of over the wall:

Less security: Using unreliable circumvention services may lead to user privacy and data leakage.
Poor stability: Using circumvention services may lead to unstable network connections and affect the user’s network experience.
Legal risks: Using circumvention services in some countries and regions may violate local laws and regulations, resulting in legal risks.
Unable to access specific websites: Some websites may detect whether the user uses circumvention services, and if detected, may restrict or prohibit the user’s access.