Function Used to Compare 1 Cell against an Entire Column

What is the function or formula i would use to compare one cell against an entire column.


Example:

I have two columsn (A and B)

Column A has 2500 rows
Column B has 2300 Rows


there is a difference of 200 and i need to find and pull out those 200 missing files.


So i need to know the function that compares the first cell from column B against the entire Column A to see if it is present. If it is present, then return a blank and if it is NOT there, then report back the value of the cell from Column A.


Thanks in advance and hopefully someone can respond as soon as possible, as i need to get the results reports back asap.

thanks