What is the difference between ereg_replace() and eregi_replace()?

ereg_replace( string $pattern , string $replacement , string $string )
eregi_replace( string $pattern , string $replacement , string $string )
This both function scans string for matches to pattern , then replaces the matched text with replacement .
eregi_replace() function is identical to ereg_replace() except that it ignores case distinction when matching alphabetic characters.