The most concrete and noticeable difference is where your listing would appear in the (SERPS) stands for search engine results page under each method.
Where they are presented:
As you know, the PPC listings on a Google results page are displayed as the top two or three listings. However, there are not always PPC ads in the top region, and generally you’ll find that for search phrases where there are a lot of firms bidding for traffic. When only a few firms are competing for the paid posts.
The next key difference is the traffic potential of each method. Generally its much faster to obtain paid listings. It hardly takes a day or so to set up a campaign, though it can be an ongoing process to really manage it efficiently.
What is the Cost?
Basically, PPC (pay-per-click) literally costs per click. In Yahoo when you bid for position – the higher the bid the higher the position you’ll get. With Yahoo, it’s a set price for each click.
Google’s pricing is much more dynamic, it’s not really possible to give a true cost, rather an average cost is used.
SEO doesn’t charge “per click”. Occasionally it’s referred to as “free” traffic, being that you don’t pay per click. Therefore, the cost is simply much less tangible – though it does exist. Fundamentally the costs for SEO are the costs of building a great site, optimising your HTML code, building awareness about your site online (including attracting links to your site), and if possible hiring an SEO expert as a consultant. It is very expensive, especially when you have a new website or if your site does not currently have much awareness and traffic.
So all the above SEO tips and tricks are very important for you to follow if you want to flourish your online business.