Data is collected by devices and expeditions that are part of numerous scientific projects and ongoing efforts. Many of these efforts sustain their own websites where they publish the data periodically or as a live stream. We call these Raw sources. For example, the SESAME project website (sesame-ip.eu), now defunct, contained announcements of the data it periodically collected.
Repositories store data from multiple sources that use these repositories to archive their data and make it more publicly available. The SESAME project data discussed above was archived at the Pangaea data repository (pangaea.de) and is available there to date, even though the SESAME project webpage is long gone.
Portals provide an interface to search in multiple repositories but do not host the data themselves. For example, dataone.org is a portal through which one can search multiple repositories and find the SESAME project data now hosted on PANGAEA.