In Japan, Japan Rail (JR) is a name that can be found across the country. It comes in many flavours. There’s the green JR East that most people will see in Tokyo, the blue JR West found in Kansai townships, the orange JR Central that serves everything between Kanto and Kansai regions, and more. In Hokkaido, there is the light green manifestation of JR known as JR Hokkaido.
In Sapporo, almost all the JR trains must go through Sapporo Station. This is probably the busiest train station in all of Hokkaido seeing about 90,000 passengers a day go through its doors. If you walk through the station around 6pm, you will feel the rush of 90,000 passengers a day.
If one must get to destinations beyond Sapporo or outside of the subway system, then JR is one way to do it. You can think of JR as a commuter rail system serving the “suburbs” of Sapporo. JR Hokkaido is more than just a suburban commuter rail, but for the purpose of getting around the outer areas of Sapporo, that’s the closest description that matches its services.