The most obvious difference is the price tag that comes with these two techniques. You are paying for the clicks that PPC sends your way, whereas the clicks from SEO are free. Getting to the top of the SEO tree for your most lucrative search terms requires hard work. Getting to the top of the PPC tree for the same search terms requires money (just how much is dependent on the competition for that particular search term) and work. Both PPC and SEO require hard work researching keywords so that you know which search terms to buy (for PPC) and which terms to optimise for (SEO). Different creatives per search term or group (PPC) and different HTML coding for each page of your site (SEO) both need to be written to entice customers. SEO has the added complication that the title tags need to be written with the search engines in mind as well.
Both SEO (search engine optimisation) and PPC (pay per click) are two major SEM (search engine marketing) tactics. Whilst they both involve the use of marketing through search engines, they are both very different tools. The major difference of course is that PPC is a 'paid' service, and whilst many people do pay SEO experts to manage and deliver campaigns, an expert in SEO simply requires time and not money.
SEO vs PPC
SEO is a 'natural' strategy. Optimising your website requires a very organic campaign. Creating genuine content that is useful to others and creating links that are relevant is what Google and the others like to see! Manipulation of the search engines to improve rankings can be a short term solution, but invariably this type of behaviour (known as 'black hat' SEO) will be spotted - potentially leading to a ban of the website.