Subject search, uses Library of Congress subject headings, e.g.:
KeyWord search, searches the title, contents, series, etc.:
By adding the * you will find all variations on that term (e.g. witch, witches, witchcraft)
Author search
For example: If you change the field to "SUBJECT" and search for "James, Henry," you may find a result like:
Full-text; search more than 1,000 U.S. historical newspapers published between 1690 and 1992; titles from all 50 states; explore America from 18th-20th centuries.