Conditional Formatting Based On Changing Dates

I am trying to keep on top of dates that are changed weekly based on last weeks dates, but i need to highlight the changed cells only.

Example:

A1 = Forecast Date
B1 = Previous Weeks Date

A1 changes daily - it is given to us by a supplier who generates their dates from a large list
B1 is the cell i want to highlight if it is different from A1.

Now my first thought was simple conditional formatting, so i highlighted column A & B and set the rule to highlight duplicates. This of course checks across all the cells and sees the same date and therefore all the cells got highlighted.

So essentially want to set the rule to compare A1 with B1 only (then A2 with C2, A300 with C300 etc) but not look for duplicates between A1 and C300.

I assume i could highlight each set of cells and set conditional formatting, but assume there is a simple bit of formula i could use?

My first thought was to use the $ sign and fix the cell references (absolute reference isnt it?) but wont give me the option to search for duplicates using formulas so assume i have to write my own formula?

Essentially i want to say if the 2 cells are next to each other, check for a change, highlight if true, ignore if false but has to ignore any other date within the workbook.

Im sure its simple, but dont know enough to do it successfully! any help will be appreciated!