A. Stateful multilayer inspection firewalls are more expensive and require competent personnel to administer them, while application-level gateway firewalls evaluate network packets for valid data at the application layer.

B. Stateful multilayer inspection firewalls track and maintain session information between hosts, while application-level gateway firewalls control input, output, and access across applications or services.

C. Stateful multilayer inspection firewalls focus on inspecting packets at the application layer, while application-level gateway firewalls primarily filter packets at the network layer.

D. Stateful multilayer inspection firewalls filter traffic based on specified application rules, applications, or protocols, while application-level gateway firewalls allow unknown traffic up to level 2 of the network stack.