The two are actually not different types of search, more likely they reflect the user's intent. I'll try to put it in simple words: Organic search is your normal search query, that does not include paid advertisements. For example if you search "running shoes Oregon" all the results, apart from the companies that paid the search engine to get a top listing, are organic results. Semantic search tries to understand the contextual meaning of words and guess the user's intent. So when you search "How can I get to Oregon?" it will logically assume that you are looking for travel options and will bring you bus/train/plane schedules even though you did not mention any of those keywords in the search. A big step in the semantic search improvement was the Hummingbird update of the Google algorithm. In the same example, all the results you will get that are not paid ads, would also be organic search results. So in this case, you are performing both a semantic and organic search Hope that helps a little