How to quickly check if two columns in Excel are equivalent in value?

This is the sort of thing array formulas were designed for. You just need one cell, one formula to give you a comparison:

=AND(A2:A11=B2:B11)

Enter the formula by pressing Ctrl+Shift+Enter. If done correctly it will appear as the following:

{=AND(A2:A11=B2:B11)}

EDIT:

For a case-sensitive comparison, the equals operator will not work. Instead, the EXACT() function should be used. Also enter this as an array formula.

{=AND(EXACT(A2:A11,B2:B11))}

You can use the =AND() function on the third column. This function will return TRUE only if all the entries in the third column are true, otherwise it will return FALSE.

I know this is an old question but here is my answer. If the two columns contain numbers only, then you can just find the difference between the numbers. If all the results are zero, then the two columns are equal. If not, then you'll have a non-zero number at the location.