1. read one line at a time using 'while' or read and store in 2 arrays line by line. (open, while, @file1, @file2, '<')
2. 'split' the line with '$#$' in both the arrays/lines. (split, @array1, @array2)
3. In a subroutine compare first, second and  third field of the array1 with first, second and third field of the array2 respectivey, for the difference.
(for time comparison you can use Date::Manip or Date::Calc module) (&subroutine)
4. write the result in a file to create a report. (open, '>')