In my view, SEO is a technique in which we optimize and promote our website or a web page in a manner so that it can easily read and evaluated by the search engine crawler easily based on the keyword entered by an user in any search engines. I mean SEO includes all the way which makes our website or webpages easily available to a search engine crawler. It is mailnly oriented for making enormous backlinks. In contrast, SMO includes all the techniques by which we make our website or webpage more visible across the Internet. It is mainly targated to make our webpages or website visible everywhere across the Internet as possible as we can so that a visitor find a link of website or webpage and may click to visit our page or site willingly or unwillingly sometimes like on an ad or banner running or more similar functionalities.
We must know that both techniques are complementry to each other and should not be denied any one of these two for the best promotion of the website or any webpages.