Resolution and Accuracy (App Note)

Resolution is not the same as accuracy.  Resolution describes how small of changes you can detect in a measurement, while accuracy describes the difference between a measurement and the actual value.  For example, you might make a thermocouple measurement where you can detect temperature changes of 0.1 degrees, and thus have a resolution of 0.1 degrees, but the accuracy of the system might only be ±2.0 degrees.  If you get two readings of 49.9 and 50.0 degrees, you know the temperature changed by 0.1 degrees, but you only know that the temperature is somewhere in the range of 48.0 to 52.0 degrees.

For more about resolution, see the "Noise and Resolution" application note.