Automated SEO involves managing your website's SEO through SEO software with some of them providing facilities like article submission, forum posting and social bookmarking.
Manual SEO on the other hand, requires a team of SEO experts to perform that task, either from a heired SEO agency or through an in-house SEO team, working for the same. Both manual and automated SEO, have their own merits and demerits and choosing the best one for your business depends on the software you use, the time you wish to and may spend on SEO activities and the expenses you can afford.