There is an agreement between ESA/EUMETSAT on the European side and NASA/NOAA on the American side that the burden of Earth observation is shared.
For operational polar satellites, Europe takes care of the morning orbits and the US does the afternoon orbits. Both sides share (or intend to share) all data in Near Real Time (NRT).
Also sensors/instruments are exchanged and mounted on platforms (read: satellites) from the other partner in the agreement. This can mean that a sensor built in the US can be flown on a European satellite.
Nowadays the aim at space agencies/operators is to avoid duplication of sensors and share what there already is. In this way a reduction in funding for Earth observation can be achieved. However, it should not drop below the minimum required to keep your end of the agreement and also needs to be enough to keep the knowledge 'current'.