Basically, imagine that NASA is an inefficient huge gas guzzler - say, a Hummer. Imagine that ESA is a small fleet of more gas efficient but boring compact cars - say, a Saab representing Sweden, a Volvo representing Germany, a Fiat representing Italy... you get the idea. Let's say there's about 11 cars, plus a bicycle from Canada I guess. Now, somehow stuff all those cars into the Hummer, put a rocket on it, and launch it to Mars.
You forgot to mention that Canada is also sending the cool robotic arm that drives the rocket.
But it does move! -- Galileo Galilei