How can I best compare two HashMaps with similar keys to get entry sets that are in one but not the other?

I have two HashMaps created from two different hierarchal file structures, one representing Excel files and the other schema definitions. For example,
Map<String, String> xlsMap = new HashMap<String, String>();
Map<String, String> xsdMap = new HashMap<String, String>();
I have a class that populates each with keys that are an identifying name that is common to both. In both cases, the values are the full path and filename where the spreadsheets and schemas reside. Assuming sample values like the following:

xlsMap.put("Parent1","C:\user\documents\Spreadsheets\Parents\Parent1.xls");
xlsMap.put("Child1","C:\user\documents\Spreadsheets\Parents\Dependents\Children\Child1.xls");
xlsMap.put("Child2","C:\user\documents\Spreadsheets\Parents\Dependents\Children\Child2.xls");
xlsMap.put("Dog1","C:\user\documents\Spreadsheets\Dependents\Other\Dog1.xls");
xlsMap.put("Cat1","C:\user\documents\Spreadsheets\Dependents\Other\Cat1.xls");

xsdMap.put("Parent1","C:\user\documents\Schemas\2017v1.0\Parents\table1.xsd");
xsdMap.put("Child1","C:\user\documents\Schemas\2017v1.0\Parents\Dependencies\Child1.xsd");
xsdMap.put("Child2","C:\user\documents\Schemas\2017v1.0\Parents\Dependencies\Child2.xsd");
xsdMap.put("Dog1","C:\user\documents\Schemas\2017v1.0\Dependencies\Other\Dog1.xsd");
xsdMap.put("Cat1","C:\user\documents\Schemas\2017v1.0\Dependencies\Other\Cat1.xsd");
xsdMap.put("Cat2","C:\user\documents\Schemas\2017v1.0\Dependencies\Other\Cat2.xsd");


This indicates a new table ("Table1Cat2") is needed. I have another class, xlsGen, that will generate a new spreadsheet given the version of the xsd, the filename of the xsd, and the destination directory for the spreadsheet. So for this small example, I would like to: 1) determine when a new table is needed; and, 2) create an ArrayList of xlsParameters that I can pass to the xlsGen.createSpreadsheet method. So the ArrayList would look like
{["2017v1.0","C:\user\documents\Schemas\2017v1.0\Dependencies\Other\Cat2.xsd","C:\user\documents\Spreadsheets\Dependents\Other"]}. In this case there is only one but there could be numerous new tables. I think I could probably get this done by iterating through the schema file structure one at a time then iterating through the spreadsheet file structure to determine the schemas that don't match. However, there are currently 240 some tables that would mean 60,000 iterations and I'm sure there must be an easier way. As always, I appreciate any help the experts might provide.