JUNOS Software for security platforms supports NAT and PAT; a traditional router does not support NAT or PAT.
JUNOS Software for security platforms does not forward traffic by default; a traditional router forwards traffic by default.
JUNOS Software for security platforms uses session-based forwarding; a traditional router uses packet-based forwarding.
JUNOS Software for security platforms performs route lookup for every packet; a traditional router performs route lookup only for the first packet.