Organic search results are those which come from the algorithm used by the search engine; paid results are just that – links that come from advertising dollars being spent to place them on the results page. Paid results may be annotated with sponsored content or set apart with a shaded box, or even placed into an area of their own, such as a sidebar.
The main difference between organic and paid traffic is, paid traffic stops when yu stop paid marketing but in case of organic traffic, once your website ranks and is on the top of search engine then you keep on getting organic traffic.
Direct traffic usually refers to traffic from sources such as bookmarks, favorites, saved browser history, or direct url iteration into the browser.
Organic traffic generally refers to traffic from search engines that is of the non paid nature. However used in broad strokes it could refer to any traffic coming in from a non paid nature which does include direct traffic.
Difference between organic traffic and the paid traffic are
Paid traffic is the one way to do advertising through paid services. In paid service you can increase your traffic for better results it is very effective.
Organic traffic is the traffic or says that natural seo generally takes more time to execute but can yield longer term results.
Organic traffic is traffic that comes to your website as a result of unpaid search results. Frequently, one of the goals of SEO is to increase organic traffic. Other types of traffic include: Pay Per Click (PPC) - traffic from ads that cost money.
Paid traffic is one of the best ways to get traffic in your domain site but for this, you need to pay for the advertise that are shown on the search engine.
Organic traffic is what most marketers strive to increase. This traffic is defined as visitors coming from a search engine, such as Google or Bing.
Traffic coming through search engine is Organic Traffic (SEO) while Traffic coming through advertisements is Paid Traffic (SEM). The best traffic is Organic Traffic.