According to ISO 32000-1, when viewing or printing a PDF document, the contents should be clipped to the Crop Box (if there is no Crop Box defined in the document, it takes the Media Box instead). The Imaging Engine (using the Adobe APPE kernel) is ISO 32000-1 compatible, so it clips the Ripped content on the Crop Box. But FlexRip/Nexus doesn't, resulting in objects outside the Crop Box to be visible on the output.
The different Page Boxes are visible in Adobe® Acrobat® or ArtPro+:
The FlexRip ticket will first normalize the PDF. During normalization the Crop Box gets lost (meaning that it will always end up being the same as the Media Box). All objects outside the original Crop Box become visible in the output.
The Nexus Rip doesn't use the Crop Box to clip the contents. This results in objects outside this Crop Box to become visible.
Users complaining about objects outside the Crop Box being removed can adapt the job to get similar results as FlexRip/Nexus.
Use the Optimize PDF Document to set the Crop Box to the Media Box.
If there is no Trim Box, its default value is the Crop Box. As we set the Crop Box to the Media Box, we can first set the Trim Box to the original Crop Box:
The Ghent Working Group (GWG) industry association recommends not to set the Crop Box at all, but to let it default to the Media Box. That way, whichever Page Box is selected for Ripping, none of the content within that box will be clipped out.