If overdone, some engines and directory's will downgrade the page due to what they term as spamming. In general, a keyword that appears closer to the top of the page or area will be more relevant. However, sometimes it helps to have a keyword in the middle of an area, or even toward the end of the area. Each variation of a keyword, such as the plural form of the word, is treated like a separate keyword. Each variation of a keyword, such as the plural form of the word, is treated like a separate keyword.
Submission is a part of positioning.
All of this information is generated via comparisons between the top websites in any category that is being optimized for top ranking. A laborious project at best. A directory differs in that it only enters sites that are directly submitted to it and in stead of crawling a site they send humans to inspect and decide if your site is worthy of a listing. A search engine generally returns the result of a search ranked by 'that search engines' indexing criteria. This formula varies widely between search engines.