The results display takes a while to get used to, particularly the annoying, smiling yellow ball. The degree of the grimace represents how close a match to the search query the answer is. OKRA limits output to 50 records. On some queries, it came close to Four11 in quantity but other searches fared less well. Except for common names, a simple name search usually succeeds best.
All matches is the standard search.
The exact match requires that the full name match exactly, including both first and last names. However, the exact match does not need to be exact on search terms included in the second search box. The latter two categories start using fuzzy matches, where Gibson matches Johnson, Jane matches Janet, and Baker matches Barker, Becker, and Whitaker. While such search functions are interesting, it is only useful when you are not sure of the name of the person. Most people trying to find an email address usually know the name of the person.