SEO is Search Engine Optimization and SEM is Search Engine Marketing. SEO is related to the Organic Search / Rank / Traffic while SEM is related to the Paid advertisements. Based on the number of click to the website - SEM is a Paid form of advertisement. An Digital Marketing Course can help you understand all the aspects of Digital Marketing. If you are in Mumbai then go for ITM Digital Marketing Institute, they offer 7 months weekend Course that covers all the major Digital Marketing Courses including SEO, SEM, SMO etc. Check out the institutes website to know more details.