SpellingCorrection is an option for StringMatchQ, Names and related functions which specifies whether strings should be considered to match even when a small fraction of the characters in them are different.
The default setting SpellingCorrection -> False requires exact matching.
?name effectively uses SpellingCorrection -> True when it cannot find an exact match for name.
See The Mathematica Book: Section 2.7.3.
See also: IgnoreCase.