SEO (Search Engine Optimisation) refers to the methodology of creating and editing web pages in such a way that their form and content are suitable for processing on Internet search engines. The goal of SEO is to get a better position and targeted visitors in search results.
SEO is a controversial technique because it is used both for the benefit of the site reader and for the benefit of the site builder.
PPC (pay-per-click) is one form of advertising. An advertiser only applies if a user clicks on an ad in search results, on Facebook, or else on a web page. PPC brings relevant visitors and potential customers but needs to be set up well and efficiently. PPC is a broad area that includes tools like remarketing. PPC is well measurable, you can see if it is good for you or not.