Accuracy: Accuracy refers to the difference between true value and that obtained from a very large number of tests.
Precision: Precision refers to degree of reproducibility of results of an experiment or method as distinct from its accuracy. The precision of a measurement depends upon the measuring device and the skill with which it is used.
For example, distance between two cities is 200 km. The distance between two cities can be measured by an odometer fitted in automobile, (car, bus, truck). If an odometer records 1 km for every kilometer passed over, it will record the distance between two cities as 200 km. If it records 0.9 km for every 1 km passed over, the distance recorded will be 180 km. Therefore, the odometer reading is not accurate.
But if the odometer records 180 km each time it is used for the trip, the odometer reading is precise. The measurement has high degree of precision between the same reading (180 km) is reproduced time after time but the accuracy is poor because the odometer is not calibrated properly and there is difference between the exact value (200 km) and the value recorded (180 km).
