A measure of accuracy (typically in LSBs) of an A/D converter. It includes all non-linearity and quantization errors. It does not include gain and offset errors of the measurement circuitry. As a measurement, it is the deviation of the measured data from the ideal data relative to a straight line drawn through the measured endpoints.
A measure in LSB of the accuracy of an ADC. It includes all non-linearity and quantization errors. It does not include offset and gain errors of the circuitry feeding the ADC.