And I thought I gave you the 2nd best answer here with the Date::Manip solution. To get into more detail:

use Date::Manip;
# This would give you h:m:s difference
Delta_Format(DateCalc($day1, $day2), 2, '%hh h:%mv m:%sv s');
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If you could post a concrete example of what you are looking for, or what has been wrong with the solutions offered to you, that would make it easier for us to help you.