(SEO) Search Engine Optimization vs (SEM) Search Engine Marketing
Search Engine optimization (SEO) is the way to improve the quality and amount of site traffic to a site or a website page from search engines. SEO targets unpaid traffic (known as "common" or "natural" results) instead of direct traffic or paid traffic whereas, Search Engine Marketing (SEM) is a type of Internet marketing that includes the advancement of sites by expanding their visibility in search engine result pages (SERPs) basically through paid publicizing.
For example, I have a website on Home Decor, Bath towels, Face Towels, Hand Towels, Cotton bath Towels etc so, what is more, beneficial for the website, organic or inorganic method to improve the visibility. I more focus on Organic search as I will get genuine traffic from search engines.