Two geometric figures are homothetic if one is a dilation of the other.
Two figures are similar if one is an enlargement, a reduction or a reproduction of the other. For the two figures to be homothetic, they must have the same position, that is, their corresponding sides must have the same direction and the lines that join their corresponding vertices must be concurrent.
Triangles ABC and A’B’C’ are homothetic.
The similar triangles DEF and D’E’F’ below are not homothetic. The corresponding sides are not parallel and the lines EE’, FF’ and DD’ are not concurrent.