They approach it differently, store it differently, and present it to the world differently. While each style has its value, when it comes to finding information on the web, directories and search engines are different. A search engine is a program that looks for documents that contain specific words or phrases. A searchable directory is a database of web sites, organized into categories or topics, which is itself searchable. An example of a searchable directory is Yahoo.
Web browsers are fully customizable.
You have the option of changing the size of the text and style of font that is displayed. Sites with no links to other pages may be missed by spiders altogether. Once the spiders get to a website, they typically index most of the words on the publicly available pages at the site. Whenever you search the web using a search engine, the search engine will scan its index of sites and match your keywords and phrases with those in the texts of documents within the engine's database. Search engines use special software programs to search their indexes for matching keywords and phrases, which then presents their findings to you in some kind of relevance ranking.