I thought they were the same? if so, where did the name come from? it seems pretty obvious 'exhause pipeS at the HEAD of the exhause system' anyway, yeh i know, dumb question. but enlighten a bro willya fellas?

 

Its basically the same thing. first off a lot of manifolds are cast iron instead of the custom bent steel. Also, the aftermarket has a big habit of calling these pieces headers. One thing to be careful of is that a lot of headers have tine plates where they bolt to the head. This can cause the bolts to loosen in a rather short time period and cause blown ehaust gaskets. If you go with a set of headers do some research on who says the best ones are, and by all means keep an eye on the bolt torque spec.
Jim