Seo stands for search engine optimization while PPC stands for pay per click. Seo helps a site to rank organically in the search engines by adopting various strategies for making a site popular on the World Wide Web. On the other hand, PPC is a paid channel which helps a site to rank inorganically on the search engines. Seo is a long term strategy while PPC gives you instant results and conversions.
The below infographic compares search engine optimization with pay per click.