Some of the major differences between the DOT and the SIC include: The SIC identifies industries by code number and classifies them; the DOT defines job titles and the tasks associated with them.The DOT identifies industries by code number and classifies them; the SIC defines job titles and the tasks associated with them.The SIC is not very helpful as a classification document, but it provides good information about things done in the job.The DOT provides very little if any information about industries; it just classifies them.