Hi Ed.... The NATS is normally USA/sometimes Canada.
The Worlds, being the inaugural World Championship has attracted many pilots from overseas and you can take a look at the registration on the drop down tab with the different classes being flown.
Freestyle will be on both Friday and Saturday, culminating in the trophy presentation at the gala banquet on Saturday night.
Given a choice, I would recommend the World Championship hands down.
Hope to see you there.
I noticed that you are in Ontario.... There is a strong Canadian Team attending the event.... So come on down & cheer your country along.
Regards & safe flying.
Wayne