We're getting off the point here. The original question referred to a stationary prop vs a windmilling prop, no mention of feathering and 'discing' is a red herring.
I assume we are referring to the difference in drag, in something like a PA28/Cessna 150, between an non-mechanical engine failure where the prop is still rotating and an engine seizure where the prop is stationary but not, of course, feathered.
As 4dogs suggests, this is difficult to explain in simple terms without the use of diagrams so, if you check your e-mail, h_f_d you may learn something to your advantage.