How to compare the two column in excel 2007?

you can use "IF" formula to compare both columns but your data should be properly segregated.
=IF("First cell of Column A"="First cell of Column B","Data Matched","ERROR") or =IF(A1=B1,"Data Matched","ERROR").

The control technique depends on what you want to compare.
If the data is sorted, then you can just use an "IF" statement, like IF(A1=B1;"OK";"") If you have large datasets with unsorted data, or with substantial differences, the "IF" statement is not sufficient any more.
An example in with unsorted data, if you want to check if a value of the1st column (A) is present in the2nd column (Z), you just add a column next to it with the formula: =vlookup(A1;Z:Z;1;FALSE) - and copy this formula down.
You will get an error message if the value is not present.
To do a2-way compare, you can add a check on the2nd dataset as well: =vlookup(Z1;A:A;1;FALSE) - and copy this formula down.
Then just filter out the records with the error messages to see the differences.

exemlpe column A and B In Column C, the first row, put =IF(A1=B1,"MATCH","") What this does is compares the contents of cell A1 with the contents of cell B1, and if they are equal, will print in cell C1, "MATCH".
If they are NOT equal, will leave C1 blank.