5th Gen civic weight difference...

I have this post in the JDM motor section but no one is answering. Maybe someone here knows...

Si- 2326 lbs
DX- 2178 lbs
CX- 2094 lbs

I was just wondering where that weight difference lies? Is it only in the motor? I do know the Si has 4 wheel disc brakes. Thats about it. Please give me insight.

go here:

http://civic.vtec.net/main.htm