Chicago style or Turabian style?

I have always wondered, what is the difference between Chicago style and Turabian style? The two styles are so close that they are often interchanged so I thought it would be helpful if I briefly explained the difference.

Kate L. Turabian was the graduate school dissertation secretary at the University of Chicago for almost 30 years. The school required her approval for every master's thesis and doctoral dissertation. Kate Turabian's book , A Manual for Writers of Term Papers, Theses, and Dissertations, is based on the University of Chicago Press's Manual of Style and its associated style are generally referred to as "Turabian." Her stylistic rules closely follow the University of Chicago Press's Manual of Style; however, Turabian style synthesizes the rules most important for students' papers and other scholarly research not intended for publication, and omits some of the publishing details and options that "Chicago" provides.  

Except for a few minor differences, the overall style promulgated by Turabian is the same as The Chicago Manual of Style. While The Chicago Manual of Style is focused on giving style guidelines for publishing in general, Turabian is focused on student papers, dissertations, and theses. Turabian is very different, however, from the styles that are endorsed by other institutions, such as MLA style and APA style. Turabian's key contrast with the APA style is that it was developed specifically for the purpose of being used in papers written for a class and not for publication, whereas APA was originally developed by the American Psychological Association for use in writing intended for publication in professional journals.

Additional information about Kate Turabian and Turabian style available here.