where are you getting the "oem" and "after market" parts from? same place? are the "after market" warranted to be OEM equal? are they the same part numbers?
They are almost certainly* going to be the exact same parts,,, the OEM one will have had 3 more "steps" on the parts, each "step" adding their own (40% to 100%) markup.
* you can never be -sure- until you look at the parts...