Key Words: Most web search engines are designed to search for words anywhere in a document—the title, the body, and so on. This being the case, a keyword can be any term that exists within the document. However, priority is given to words that occur in the title, words that recur numerous times, and words that are explicitly assigned as keywords within the coding.
A Key Phrase is made up of multiple keywords, or a specific combination of keywords, that a user would enter into a search engine. In SEO (search engine optimization), optimizing your site for specific keyphrases will yield a smaller number of more specific and relevant traffic.