Excel Conditional Formatting to identify Different Postcodes

[funkylad20]

I have two lists of postcodes (column A and column B)
The majority of entries are identical (i.e. A1 and B1 are the same)
On occasion the 'B' postcode will be different to the 'A' postcode.
HOW do I identify the different ones?
I vaguely recall using conditional formatting as a tool?

[ChuckFickens]

Click on b1, then click on the format menu and select conditional formatting. and set it so the fist 3 items are

1) cell value is
2) not equal to
3) type a1 into the box

then click on the format button and select how you want to display the cell if it is different, I'd suggest clicking on the pattern tab and selecting a colour.

[funkylad20]

Thank you, works a treat.
HOWEVER, it seems entries in column A have a 'space' at the end, and column 'B' doesn't always, so it is highlighitng them as different when they are not (due to the space).
Is there a way to format both columns to incorporate 8 entries maximum (i.e. WC1B_4SE is 8 characters, inclusive of the space, WC1B_4SE_ is 9...)

[TTG]

Change the drop down to Formula Is. Enter the formula as =NOT(EXACT(LEFT(A1,8),LEFT(B1,8)))

If the first 8 characters of A1 and B1 are different, the formatting you set by clicking on the format button will apply.