You get three TYPES of tables each possible of doing CHAINS... plus you can apply them PRE-ROUTING or POST-ROUTING... AWESOME...

And... AND... it is tremendously more scalable... it is actually less processor intensive as well...

For IPTABLES, you can do SNAT, DNAT, plain-ole NAT, MASQUERADING, Virtual Address Forwarding, Port forwarding, Address Mapping... defaults can be used to be Open - Except or Closed - Except... it is Stateful (wonderful there) and even that can be turned off... logging has 7 settings (no logging to "OHMYGAWD my 1TiB LOG Volume is Full Already in 20 minutes" setting)

Overall it can make traffic do anything you REALLY want it to do.