Comparing

The Compare-Object command allows collections of objects to be compared to one another.

Compare-Object must be supplied with a value for the ReferenceObject and DifferenceObject parameters, which are normally collections or arrays of objects. If both values are equal, Compare-Object does not return anything by default. For example, both the Reference and Difference object in the following example are identical:

Compare-Object -ReferenceObject 1, 2 -DifferenceObject 1, 2 

If there are differences, Compare-Object will display the results, as shown here:

PS> Compare-Object -ReferenceObject 1, 2, 3, 4 -DifferenceObject 1, 2

InputObject SideIndicator
----------- -------------
          3 <=
          4 <=

This shows that the ReferenceObject (the collection on the left) has the values, but the DifferenceObject (the collection on the right) does not.

Compare-Object has...