What is the difference between deep packet inspection and stateful inspection?

 Deep packet inspection (DPI) and stateful inspection are two techniques that are used by firewalls and other network security devices to inspect and filter network traffic. Stateful inspection allows visibility on Layer 4 (transport layer) of the OSI model, which means it can track the state of TCP or UDP connections and filter packets based on source and destination IP addresses, ports, and protocols. Deep packet inspection allows visibility on Layer 7 (application layer) of the OSI model, which means it can inspect the contents and payloads of packets and filter packets based on application-specific criteria, such as signatures, keywords, URLs, or behaviors. References:

Understanding Cisco Cybersecurity Operations Fundamentals (CBROPS) v1.0, Module 2: Security Monitoring, Lesson 2.2: Network Security Monitoring Tools

Cisco Certified CyberOps Associate Overview, Exam Topics, 2.2 Describe the impact of network security monitoring tools on data privacy