diff --git a/python/eups/app.py b/python/eups/app.py
index 5185c37b..419ada2b 100644
--- a/python/eups/app.py
+++ b/python/eups/app.py
@@ -18,7 +18,7 @@
 from .utils import cmp_or_key
 
 def printProducts(ostrm, productName=None, versionName=None, eupsenv=None,
-                  tags=None, setup=False, tablefile=False, directory=False,
+                  tags=None, setup=False, tablefile=False, difference=False, directory=False,
                   dependencies=False, showVersion=False, showName=False, showTagsGlob="*",
                   depth=None, productDir=None, topological=False, checkCycles=False, raw=False):
     """
@@ -32,6 +32,8 @@ def printProducts(ostrm, productName=None, versionName=None, eupsenv=None,
     @param setup           restrict the listing to products that are currently
                               setup (or print actually setup versions with dependencies)
     @param tablefile       include the path to each product's table file
+    @param difference      Print the relative complement (set difference) of declared version
+                              products to setup products
     @param directory       include each product's installation directory
     @param dependencies    print the product's dependencies
     @param showVersion     Only print the product{'s,s'} version[s] (e.g. eups list -V -s afw)
@@ -97,7 +99,25 @@ def printProducts(ostrm, productName=None, versionName=None, eupsenv=None,
 
             raise ProductNotFound(productName, versionName, msg="Unable to find product %s" % msg)
 
+    if difference:
+        if versionName:
+            raise EupsException("--diff does not make sense with a version")
+        if dependencies:
+            raise EupsException("--diff does not make sense with --dependencies")
+        setupProducts = set(eupsenv.getSetupProducts())
+        dependentProductList = eupsenv.getDependentProducts(productList[0])
+        dependentProducts = {x[0] for x in dependentProductList}
+        productList = list(setupProducts - dependentProducts)
+        if not productList:
+            return 0
+
     productList.sort(key=lambda p: (p.name, p.version))
+
+    if difference:
+        # Insert the main product name at the front of the list, to be printed first
+        productNameIndex = [i for i, p in enumerate(productList) if p.name == productName][0]
+        productList.insert(0, productList.pop(productList.index(productList[productNameIndex])))
+
     if dependencies:
         _msgs = {}               # maintain list of printed dependencies
         recursionDepth, indent = 0, ""
@@ -249,7 +269,7 @@ def includeProduct(recursionDepth):
                     info += "|"
                 info += name + "|" + version
             else:
-                if productName and not utils.isGlob(productName):
+                if productName and not utils.isGlob(productName) and not difference:
                     info += "   "
                 else:
                     info += "%-21s " % (name)
diff --git a/python/eups/cmd.py b/python/eups/cmd.py
index d26d6e13..c658938f 100644
--- a/python/eups/cmd.py
+++ b/python/eups/cmd.py
@@ -455,6 +455,8 @@ def addOptions(self):
         # these are specific to this command
         self.clo.add_option("-c", "--current", dest="currentTag", action="store_true", default=False,
                             help="same as --postTag=current")
+        self.clo.add_option("-C", "--diff", dest="difference", action="store_true", default=False,
+                            help="Print the relative complement (set difference) of declared version products with respect to currently setup products")
         self.clo.add_option("-D", "--dependencies", dest="depends", action="store_true", default=False,
                             help="Print product's dependencies (must specify version if ambiguous). With --setup print the versions of dependent products that are actually setup.")
         self.clo.add_option("--depth", dest="depth", action="store",
@@ -506,8 +508,9 @@ def execute(self):
             n = eups.printProducts(sys.stdout, product, version,
                                    self.createEups(self.opts, versionName=version, quiet=1),
                                    tags=self.opts.tag,
-                                   setup=self.opts.setup,
+                                   setup=self.opts.setup or self.opts.difference,
                                    tablefile=self.opts.tablefile,
+                                   difference=self.opts.difference,
                                    directory=self.opts.printdir,
                                    dependencies=self.opts.depends,
                                    showVersion=self.opts.version, showName=self.opts.showName,