Organic SEO relies on manual or natural techniques of enhancing a site and takes more time leading to long permanent results. It takes less time but results have a shorter life.
In the violently competitive industries it is vital to be on top of Google, Yahoo or any other search engine listings to tap focused audience.
Each class of seo tools in turn has number of software developed by different corporations. It has relevancy to know which are good before you embark on using one. You can always try them out before narrowing your options and purchasing the best.
Remember, SEO tools are only tools ; one should use them with a lot of prudence lest the search engines black list you.