Clients often ask me the difference and I give them a simple answer that normally puts an end to the conversation and their questions, much like the answer shane thomas gave, but less detailed. Direct is people putting in your url in the top and organic is people searching for you. Here is an example: If I want to buy a book i type in amazon.com (direct traffic) but if i forgot where to buy a book online i search for "where to buy a book online" which directs me to amazon.com (organic traffic). When i explain it like this, a light bulb goes off and they understand. Hope that helps.
If you’ve seen ads appear at the top or right of search engines, then you already know what SEM is. When your ads display in these optimal, highly visible positions, your business can have an edge over your competition. Plus, most searchers only click on the first few results, which gives these premium ad spots a visual advantage to catch the attention of your future customers.
Now, it is not that these sites are not interested in Google users. In fact, they have hired us to help them increase their share. However, they are getting so much traffic from sites like Facebook that it seems there is less urgency about attracting this traffic and less willingness to change the site to meet organic standards. Not long ago, sites would urgently and unquestioningly abide by Google’s standards to court that traffic.