The main difference between GPW and GRUMP population grids are their inputs and outputs. GPW is simple, areal-weighted redistribution of census inputs from their census boundaries (or administrative polygons) to a uniform quadrilateral grid. The GRUMP population grid should be considered lightly modeled. Although it also uses areal weighting to redistribute population from polygons to grid, it uses urban polygons as well as administrative polygons and makes assumptions about the parameters of the assignment in those urban areas. Also, the population grid for GPW is available at a 2.5 minute resolution, whereas GRUMP is available at a higher resolution of 30 arc seconds (or nominally, 1 km). GRUMP data products also include settlement points and urban extent databases.