The prefinished flooring discussed below refers to solid hardwood that is 3/4" thick. It is stained and finished at a factory so it can be installed and ready to go without staining or sanding. This type of flooring has continued to gain popularity because of it's advantages.
Site-finished flooring, on the other hand, is installed in it's raw form and then sanded, stained and finished on site. This option has advantages as well. Ultimately, it is up to the homeowner to decide which option will best serve their needs and preferences . . .