As the title states, I have searched and can not find anything on the topic I am wanting to know what the differences are between the two even know the whole front ends are the same. Thanks

 

JDM Si used a headlight shaped and fitted the same as the USDM ones. However, the JDM Si uses a plastic housing (wait did I get that backwards? i cant remember anyone, opsit of ours anyway), as well as a Single H4H bulb instead of our dual bulb system for High and Low beam.

 

that is correct. we have glass housing as the edm/si has plastic and uses the h4h headlights

 

basically:

ZC = 1 bulb and 1 chamber ... as opposed to the USDM ones which had a 9006/9005 in a dual chamber