Search engine optimisation (SEO), is the process of increasing the visibility of your website through an organic process, including things like keywords, images, videos and location.
Pay per click (PPC), is the process of setting up adverts on Google and Bing. Once set up, you’ll immediately appear at the top of searches for your desired keywords.
It does depend on Google, and other search engines bots reading your data but results typically are seen between 3-6 months. This also depends on your industry, key phrase competition and effort taken in your SEO tasks.
PPC is almost immediate. Once your adverts are live, they will appear on searches. You’ll see increased traffic straight away.