Champ car as in Indy cars..
In the US, it used to be one indy car series called CART....
That split up into two leagues, IRL (Indy Racing League) and the Champ Car World Series...
Formula One is international, IRL/Champ car is (basically) a US series *BUT* Champ car has some venues outside of the US (Toronto, Edmonton, Montreal, South Korea, Australia, Mexico
City) as does the IRL (Motegi Japan,)
F1 is much more international than IRL or Champcar, though...