Network security refers to the measures taken to protect a computer network from unauthorized access, misuse, modification, or disruption. It involves the implementation of various security controls, such as firewalls, intrusion detection systems, encryption, and access controls, to safeguard the network and the data transmitted over it.

Penetration testing, on the other hand, is a method used to evaluate the security of a network by simulating real-world attacks. It involves conducting controlled attacks against a network or system to identify vulnerabilities and weaknesses that could be exploited by malicious actors. Penetration testing can help organizations identify and address security flaws before they are exploited by attackers.