How big is a GeoPDF document and is it larger or smaller than a geospatial PDF document?

It depends almost entirely on how much data is being displayed in the document. Geospatial datasets can vary over several orders of magnitude ranging from bytes to terabytes, and so too do GeoPDF and all PDF documents. Here are some general rules:

• If no feature attributes are placed in the GeoPDF document, the PDF representation (e.g., the PDF file) is generally smaller than the data used to create it.
• If all the feature attributes are included in the PDF file, it’s often larger, sometimes substantially so, than the data used to create it, although using GeoPackage feature attributes with TerraGo Publisher for ArcGIS can mitigate this substantially.
• One case where GeoPDF documents are almost always larger than their non-TerraGo analogs is when the TerraGo Publisher for ArcGIS capability to include layers with scale-dependent visibility is used. In this case, Publisher will add layers that wouldn’t be added otherwise, meaning that more information was packed into the resultant document at the cost of the space to store it.