What is the difference between Science.gov and collections/gateways to government science information made available elsewhere?
The major difference is source and authority of the information. Rather than automatically collecting the sites using spiders as private sector gateways might do, the science.gov sites are selected by agency information managers and librarians as representing authoritative government science information. The information content results from government-funded research and development or similar activities in which there is a U.S. Government investment. The agencies are responsible for the content of their respective sites that are included in Science.gov.