Explanation:
WYXV is quadrilateral.
the reason are the undefined angles at W and V (they are equal, but not necessarily 90°, so the shape could shrink or extend between W and V)
ABCD is a rectangle.
AB and CD are parallel and equally long. and C is 90°.
that means then that the other angles must be 90° too, or either the parallel or equally long criteria would be violated.
PQSR is a parallelogram.
PQ and RS are parallel and equally long.
that means that PR and QS must also be parallel and equally long. we just don't know the angles, they could be anything. and therefore this is not a rectangle but a more generic parallelogram.