Search Engine Optimization is a part of search engine marketing. In Search engine marketing it encompasses with PPC Management, Search Engine Optimization, Affiliate Marketing, Banner Advertising, Paid advertising. Search engine marketing or internet marketing is basically used to get the maximum conversion from the website, to increase the sales, to increase the ROI.
SEM process can take 8 months to a year and seo will complete within 3 to 6 months. Search Engine Optimization is a subset of search engine marketing.