Two figures are congruent if they are the same size and shape – that is, if their corresponding angles and sides are equal. Congruent figures are named in the order of their corresponding parts. ΔDEF is congruent to ΔABC.
Two figures are similar if they are the same shape but not necessarily the same size – that is, if their corresponding angles are equal and their corresponding sides are in proportion. We say, ΔABC ~ ΔEFG.