there's no built-in tool for this in OPERA. But here's what you could do:
For every configuration area there's a matching report in OPERA (all these reports start with the "cf_" prefix). You can Print to File the necessary reports selecting the Delimited option. This produces CSV files that can easily be imported into Excel. From there on it's just a matter of opening the reports for the two shells in different screens and compare.
Just go to PMS > Miscellaneous > Reports and pick the Configuration Report Group.
Select your report, check "Print to File". Fille Format = Delimited > Tab
OK > File > Save to the desired location (the extension will be "txt" but you'll be able to open it with Excel easily)