To compare samples, the fastest way is to use CC Capture Color Inspector: QuickChecker

 QuickStart QuikChecker

Three easy steps: 

1. Measure the first sample.

2. Measure the second sample.

3. Select as a reference the first measured sample or any other measurement or any source of the reference

The report shows most of the popular color difference formulas. 

As an option, a Substrate can be measured in advance. That will add an additional Ink GPS report with the Perfarb graph!