Many authors and professors are treating the subjects work system design and work study as synonymous.
It will be more appropriate to think of them two separate subjects and develop them. Work systems design may start from identifying the sites for various facilities, and involve determining the locations of various buildings and structures at various sites, designing the buildings and structures, developing layout of equipments and departments in various buildings, designing work stations, storage facilities for WIP, and finally end with specifying standard operating procedures for each employee involved in the work sytem. All this design work requires design data and unfortunately industrial engineering profession has not so far developed as design data handbook.
Work study in contrast concentrates on methods performed by operators and it can result in redesign of the method. But work studies can also assist in developing standard methods which can be included in the design data book as the best practices for that specific job/operation/process.