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Hi Katerina and welcome to the Forum.
Not sure HOW you want to "differentiate" between the seemingly similar times (using a formula, conditional formatting, via VBA etc.) but Excel stores dates/times as numbers. The formatting of the cell may make times looks the same (though they actually differ by seconds in reality).
For example, my formatted cell shows "06/02/2021 09:07" (in UK format) but clicking in the cell shows the seconds "06/02/2021 09:07:00" in the formula bar and formatting the cell as a Number reveals (on clicking) the stored number as 44233.3798611111.
The numeric value for a similar looking cell but just one second later is 44233.3798726852. Both numbers look the same (in the sheet) but are quite different. This is detailed in Don's tutorial Vlookup on Dates and Times in Excel
Taking the simplest way to "differentiate" between date/times, you could calculate the time in seconds between dates in your column using this simple formula (but changing the cell references in bold):
=(A5-A4)*86400
Be sure to format the result cell as a Number not General (and adjust the formatting for number of decimal places to suit yourself).
That formula just subtracts the two date/time numbers (which are fractional numbers of days) then multiplies the result by the number of seconds in a day (24*60*60=86400) to give the number of seconds.
Hope this helps.
REVISION 1: If your looking to check if rows in one sheet of your file are matched in another sheet ("ncr"), the worksheet function COUNTIFS can be used. In my revised file (attached), I've left your VLOOKUP formula in the first 2 or 3 rows of sheets SEF and ACF but copied some values into some additional rows below (and for demo purposes, I've changed some bits to create mismatches). In new column J of SEF, I've used this formula (e.g. in cell J2):
=IF(COUNTIFS(ncr!A:A,A2,ncr!F:F,B2,ncr!D:D,D2,ncr!E:E,E2)=1,"Y","Not found or duplicated in NCR")
and likewise in sheet ACF.
The COUNTIFS part (in bold) counts the number of entries in ncr which match certain parts of row 2 in SEF. Each pair of arguments comprise a lookup range and a criteria (=value) e.g. the pair "ncr!A:A,A2" is TRUE if A2 is found in ncr column A. Likewise for B2 is found in ncr column F etc. Each time all pairs are TRUE-i.e. (Flight Date (updtd), Reg.No., Company name and Flight code all match- it counts as 1. For a unique match, COUNTIFS would return the value 1; 0 if it's not matched or 2 if it's found twice etc.
Accordingly I've wrapped that in an IF function which just says Y is there's a uniqure match and a warning if it's not found (I've also added conditional formatting so the text in the columns are bold and red if the formula doesn't return "Y".
Hope this makes sense and works for you. Suggest you change some values (or correct them to see that it works.
