What is the primary difference between an application firewall and a traditional L$3/$L$4$ stateful firewall?

Application firewalls always reside in the vNIC of virtual machines, stopping threats closest to the destination as possible.

Application firewalls inspect traffic at Layer $7,$ to provide visibility at user and application behavior beyond Layer $3/4$ permit$/$deny criteria.

Application firewalls introduce more latency than L$3/$L$4$ firewalls, because unlike application firewalls, L$3/$L$4$ stateful firewalls can easily group together Layer $3$ and Layer $4$ information for fast lookups on $$blocks$$ of permit$/$deny entries.

Application firewalls are always distributed, where traditional stateful firewalls can be clustered through hardware or software.