Osaka station is the biggest station in west part of Japan. Osaka station is located at one of two biggest downtown cores, Umeda. This may make you be confused. JR Osaka station is completely same as Umeda station. You can transfer JR trains and other trains at Osaka and Umeda stations.
Even though Shinkansen does not stop at JR Osaka station, many limited express trains depart and arrive at this station. And three subway lines (Midousuji line, Tanimachi line and Yotsubashi line) and two private railways (Hankyu and Hanshin) have stations as “Umeda” station.