Nomenclature
"Imide" refers to derivatives of imide itself (NH) or its organic derivatives (RN). The organic functional group called an imide contains two acyl groups are attached to NH or NR.
Most imides are derived from dicarboxylic acids and their names reflect the parent acid Examples are succinimide derived from succinic acid and phthalimide derived from phthalic acid. For imides derived from amines (vs. ammonia), the N-substituent is indicated by a prefix, e.g. N-ethylsuccinimide is derived from succinic acid and ethylamine.
Carbodiimides have the formula RN=C=NR, they are unrelated to imides.
Source : Wikipedia