Typically they will make more noise, a duramax shouldn't be as noisy as a cummins by any means.
There is a line though where too much noise isn't right... Any way you could post a video of what you are hearing and or concerned about? Hard to verify without actually hearing it.
Something to remember is a diesel creates a LOT More pressure inside the combustion chamber so things WILL rattle. Speaking of the cummins at least, my fuel injectors are running in the neighborhood of 7,000 psi at an idle and up to around 20,000 psi at full throttle! things are going to make noise!