Building
A building, or edifice, is a structure with a roof and walls standing more or less permanently in one place, such as a house or factory. Buildings come in a variety of sizes, shapes, and functions, and have been adapted throughout history for a wide number of factors, from building materials available, to weather conditions, land prices, ground conditions, specific uses, and aesthetic reasons. To better understand the term building compare the list of nonbuilding structures.
Workshop
Beginning with the Industrial Revolution era, a workshop may be a room, rooms or building which provides both the area and tools (or machinery) that may be required for the manufacture or repair of manufactured goods. Workshops were the only places of production until the advent of industrialization and the development of larger factories. In the 20th and 21st century, many Western homes contain a workshop in the garage, basement, or an external shed. Home workshops typically contain a workbench, hand tools, power tools and other hardware. Along with their practical applications for repair goods or do small manufacturing runs, workshops are used to tinker and make prototypes.
Building
I do not believe that ever any building was truly great, unless it had mighty masses, vigorous and deep, of shadow mingled with its surface.
John Ruskin, The Seven Lamps of Architecture (1849), chapter III, paragraph 24.