Overall, I count 9 difference sources depending on the age and material of farmhouse drainboard sink that you are looking for. As such, you may see the various terms used interchangeably on this blog by me and by others who are interviewed or commenting. To verify what types of products you have and what they are made of, do your own research including consulting with the original manufacturer or your own professionals. Prewar and mid century drainboard kitchen sinks were, I believe, generally manufactured using a cast iron or steel substrate, covered with porcelain enamel. Ken in Massachusetts specializes in collecting and selling original-condition drainboard kitchen sinks. See this story.