Difference between dynamic resistance of diode and resistance of PWL model of diode
Neither for the "piecewise" (simplified) model nor for the real diode the static resistance RD is equal to the dynamic (differential) resistance rd.
Rd is always the inverse slope of the connection line between the operating point and the origin. And the value of RD is always smaller than the differential resistance rd which is the inverse slope of the tangent drawn at the Q point.