Hello, Vaishnav. SEO and Digital Marketing are closely related but not exactly the same. SEO or Search Engine Optimization, as the name suggests, is a field of study in how we can optimize our websites for Search Engines. While Digital Marketing is marketing using digital medias (such as the internet, for example)
You can improve your website's SEO in plenty of ways, depending on the type of your site. I can't really say which are the best ways for you since you didn't tell what kind of website or business that you have. But as a general rule of thumb, try using Google's Webmaster tools and other third parties site SEO checkers out there to see how well-optimized your website is in the SEO department, these tools usually tells you in which parts you're lacking.
