SEO and SMO both are the part of SEM(Search Engine Marketing).
Now SEO is an organic method to increase visitors to your website. This method includes on-page and off-page optimization to get SERPS(Search Engine Results Pages). SEO is also includes PPC (Pay Per Click.
Social media includes activities such as blogging, book marking, tagging, RSS feeds and Video and Photo sharing. It is basically a viral marketing technique used on social networking websites. The biggest advantage of SMO (Social Media Optimization) is you can expect traffic quickly in comparison to SEO.
SMO tactics can drive huge amounts of people to a website and can also determine whether a startup, website or idea will make it or not. It involves driving traffic to a website through new channels because search engines aren't the only sites that drive big traffic anymore. While it's not taking over SEO yet, it has the potential to someday soon.
