You can usually tell a directory by the list of category headings that come up after you enter a subject to search. These categories will expand into lists of subcategories and eventually into specific sites. Search engines use computer programs known as spiders that collect information from millions of web pages. You will get many more results from a search engine than from a directory, but the results are usually more jumbled and often contain web sites that you do not want. Some search pages include both directories and true search engines on the same page.
Most search engines are free to use.
Their operation is paid for by advertisements that appear on the search pages. Use descriptive words. When you enter two or more words on a search line, it will look for web sites that have any of the words on them. For example a search for France travel will locate all web sites with either the word France or the word travel. You might want to narrow the search down to Paris travel, or maybe just Paris.