I have come across this question before and for some time i was confused what would be the difference between Zen Cart preinstalled Zone Rates and this plugin "Zone Table Rates" available at here.
Alright, this is a brief summary of each purpose:
Zone Rates allows to define multiple shipping rates based on countries only, so you can setup let's say 3 (as the default) shipping rates with different countries attached to it.
Meanwhile, Zone Table Rates allows to define multiple shipping rates based on "Zone Definition", for those who doesnt know zone definition means, it is where we can setup a zone area down through states/provinces. So, for example you want to setup zone 1 covering Indonesia in Jakarta & Bali combined with USA in California & NY, we can do that easily.
Once we setup our zone definition, then we can define our own shipping rates using Zone Table Rates and attached our predefined Zone Definition to it, and you're done.