Solution:
In the given figures, angles of the triangle ABC are corresponding equal to triangle DEF and the sides are proportional to each other.
Thus, the triangle ABC is similar to triangle DEF.
Therefore, the relationship between both triangles is the proportional side lengths.
Both triangles are not of the same size as their sides are not equal.
Both triangles are also not congruent as they do not satisfy any five conditions of congruence.
Hence, the correct option is A.