A doorway is developed with a purpose of creating a higher ranking on the search Engine pages. A doorway page's content is infused with certain keywords so that it is able to gain a notable ranking. These phrases are only infused with an intention of getting the page to a higher position in the search results. This process is known as spamdexing- the practice of indexing a page in the search results using certain keywords only to lead the users to another page.
Cloaking technique is a dirty trick of SEO for search engine rankings. Using keyword stuffing technique, optimize the site which is invisible for normal web users but seen by a search engine spider. It is not a good practice of SEO. Page cloaking shows different version of one page to one user and different version to the other.