What’s the difference between “search engine registration” and “search engine optimization”?

Search engine registration is the submission of your site to the search engines. Search engine optimization is a proactive service ensuring your site will be highly visible on the engines your site is submitted to (it generally includes search engine registration). Optimization involves changes to your site code, including text, development of META tags, robots.txt, link development etc. to ensure that you are ranked highly on the search engines for certain keywords and phrases relating to your site content. This makes your site more accessible to searchers and ensures your site is found by your target audience, giving you an edge over your competitors.