SEM its a global and wide internet-marketing campaign... It is complex works on your site including maintenance of accounts on social media and interaction with users in all directions.
SEO means search engine optimization and SEM means search engine marketing.both are different from each other.
Seo stands for search engine optimization and SEM stands for social media marketing. One is really essential for page rank and another is a part of seo.
Difference between SEO and SEM: SEO is aimed at continuously refining the website in order to get friendly with both the search engine indexing algorithms as well as the user, thereby driving traffic to the site. SEM is aimed purely at marketing and advertising the business represented by the website.The main job of this technique is to promote the business, clinch a deal and trigger quick results.