Periodic behavior is highly predictable because it always repeats itself over some finite time interval. Chaos is both deterministic and aperiodic. Chaotic behavior never repeats itself exactly. Chaotic systems exhibit sensitive dependence on initial conditions. Chaotic behavior has definite form.
Agents can have their own or shared mental models.
Interconnections among agents can occur. Actions by one agent change the context for others. System behavior emerges from the interaction among agents. The system can exhibit novel behavior. Broad-brush prediction of system behavior is sometimes possible.