diff --git a/src/get_differences.js b/src/get_differences.js
index e350a66..c26b2d2 100644
--- a/src/get_differences.js
+++ b/src/get_differences.js
@@ -1,6 +1,6 @@
 'use strict';
 
-/* eslint-disable security/detect-object-injection */
+/* eslint-disable security/detect-object-injection, max-statements */
 
 var _ = require('lodash');
 var equal = require('deep-equal');
@@ -21,6 +21,22 @@ function compareRules(leftConfig, rightConfig) {
   var rightClean = _.omit(rightConfig, ['rules', 'plugins', 'extends']);
 
   var sharedRules = _.intersection(leftRules, rightRules);
+  var ruleDifferences = _.chain(sharedRules)
+    .map(function(rule) {
+      return {
+        rule: rule,
+        left: leftConfig.rules[rule],
+        right: rightConfig.rules[rule],
+      };
+    })
+    .reject(function(item) {
+      return equal(item.left, item.right);
+    })
+    .value();
+  var ruleDifferenceNames = _.map(ruleDifferences, function(item) {
+    return item.rule;
+  });
+  var matchingRules = _.difference(sharedRules, ruleDifferenceNames);
 
   return {
     pluginsMissingFromLeft: _.difference(rightPlugins, leftPlugins),
@@ -32,20 +48,9 @@ function compareRules(leftConfig, rightConfig) {
     extendsMissingFromRight: _.difference(leftExtends, rightExtends),
 
     rulesMissingFromLeft: _.difference(rightRules, leftRules),
-    sharedRules: sharedRules,
+    matchingRules: matchingRules,
     rulesMissingFromRight: _.difference(leftRules, rightRules),
-    ruleDifferences: _.chain(sharedRules)
-      .map(function(rule) {
-        return {
-          rule: rule,
-          left: leftConfig.rules[rule],
-          right: rightConfig.rules[rule],
-        };
-      })
-      .reject(function(item) {
-        return equal(item.left, item.right);
-      })
-      .value(),
+    ruleDifferences: ruleDifferences,
 
     differences: deepDiff(leftClean, rightClean) || [],
   };
diff --git a/src/get_score.js b/src/get_score.js
index 58bd86e..9f37bc6 100644
--- a/src/get_score.js
+++ b/src/get_score.js
@@ -5,21 +5,18 @@ var MAX = 100;
 module.exports = function(differences) {
   var totals = {
     rulesMissingFromLeft: getLength(differences.rulesMissingFromLeft),
-    sharedRules: getLength(differences.sharedRules),
+    matchingRules: getLength(differences.matchingRules),
     rulesMissingFromRight: getLength(differences.rulesMissingFromRight),
     ruleDifferences: getLength(differences.ruleDifferences),
   };
 
-  var totalRules = totals.rulesMissingFromLeft + totals.sharedRules
-    + totals.rulesMissingFromRight;
-  var unmatched = totals.ruleDifferences + totals.rulesMissingFromLeft
-    + totals.rulesMissingFromRight;
-
+  var totalRules = totals.rulesMissingFromLeft + totals.matchingRules
+    + totals.rulesMissingFromRight + totals.ruleDifferences;
   if (totalRules === 0) {
     return MAX;
   }
 
-  return Math.round((totalRules - unmatched) / totalRules * MAX);
+  return Math.round(totals.matchingRules / totalRules * MAX);
 };
 
 function getLength(array) {
diff --git a/src/render_differences.js b/src/render_differences.js
index 301c382..956e481 100644
--- a/src/render_differences.js
+++ b/src/render_differences.js
@@ -76,8 +76,8 @@ function printExtendsDifferences(result) {
 
 
 function printRuleDifferences(result) {
-  return 'Rules shared:'
-    + joinOrNone(_.map(result.sharedRules, bold))
+  return 'Rules matching:'
+    + joinOrNone(_.map(result.matchingRules, bold))
     + SEPARATOR
     + 'Rules missing from left:'
     + joinOrNone(_.map(result.rulesMissingFromLeft, bold))
diff --git a/test/unit/test_get_differences.js b/test/unit/test_get_differences.js
index 8047b95..b4db45d 100644
--- a/test/unit/test_get_differences.js
+++ b/test/unit/test_get_differences.js
@@ -25,7 +25,7 @@ describe('unit/getDifferences', function() {
     expect(actual).to.have.property('extendsMissingFromRight').that.deep.equal([]);
 
     expect(actual).to.have.property('rulesMissingFromLeft').that.deep.equal([]);
-    expect(actual).to.have.property('sharedRules').that.deep.equal([]);
+    expect(actual).to.have.property('matchingRules').that.deep.equal([]);
     expect(actual).to.have.property('rulesMissingFromRight').that.deep.equal([]);
     expect(actual).to.have.property('ruleDifferences').that.deep.equal([]);
 
@@ -42,6 +42,7 @@ describe('unit/getDifferences', function() {
         three: ['error', {
           setting: 1,
         }],
+        four: 'error',
       },
     };
     var right = {
@@ -51,6 +52,7 @@ describe('unit/getDifferences', function() {
           setting: 2,
         }],
         four: 'error',
+        five: 'error',
       },
     };
 
@@ -65,9 +67,9 @@ describe('unit/getDifferences', function() {
     expect(actual).to.have.property('extendsMissingFromRight').that.deep.equal([]);
 
     expect(actual).to.have.property('rulesMissingFromLeft')
-      .that.deep.equal(['four']);
-    expect(actual).to.have.property('sharedRules')
-      .that.deep.equal(['two', 'three']);
+      .that.deep.equal(['five']);
+    expect(actual).to.have.property('matchingRules')
+      .that.deep.equal(['two', 'four']);
     expect(actual).to.have.property('rulesMissingFromRight')
       .that.deep.equal(['one']);
     expect(actual).to.have.property('ruleDifferences')
@@ -107,7 +109,7 @@ describe('unit/getDifferences', function() {
     expect(actual).to.have.property('extendsMissingFromRight').that.deep.equal([]);
 
     expect(actual).to.have.property('rulesMissingFromLeft').that.deep.equal([]);
-    expect(actual).to.have.property('sharedRules').that.deep.equal([]);
+    expect(actual).to.have.property('matchingRules').that.deep.equal([]);
     expect(actual).to.have.property('rulesMissingFromRight').that.deep.equal([]);
     expect(actual).to.have.property('ruleDifferences').that.deep.equal([]);
 
@@ -142,7 +144,7 @@ describe('unit/getDifferences', function() {
     expect(actual).to.have.property('extendsMissingFromRight').that.deep.equal([]);
 
     expect(actual).to.have.property('rulesMissingFromLeft').that.deep.equal([]);
-    expect(actual).to.have.property('sharedRules').that.deep.equal([]);
+    expect(actual).to.have.property('matchingRules').that.deep.equal([]);
     expect(actual).to.have.property('rulesMissingFromRight').that.deep.equal([]);
     expect(actual).to.have.property('ruleDifferences').that.deep.equal([]);
 
diff --git a/test/unit/test_get_score.js b/test/unit/test_get_score.js
index f26f30f..e597887 100644
--- a/test/unit/test_get_score.js
+++ b/test/unit/test_get_score.js
@@ -16,7 +16,7 @@ describe('unit/getScore', function() {
   it('returns 100 for no differences', function() {
     var differences = {
       rulesMissingFromLeft: [],
-      sharedRules: [],
+      matchingRules: [],
       rulesMissingFromRight: [],
       ruleDifferences: [],
     };
@@ -28,11 +28,11 @@ describe('unit/getScore', function() {
 
   it('returns all differences', function() {
     var differences = {
-      rulesMissingFromLeft: ['one', 'two'],
-      sharedRules: ['three', 'four'],
-      rulesMissingFromRight: ['five', 'six'],
+      rulesMissingFromLeft: ['one', 'two', 'three'],
+      matchingRules: ['four', 'five'],
+      rulesMissingFromRight: ['six', 'seven'],
       ruleDifferences: [{
-        rule: 'five',
+        rule: 'eight',
         left: ['error', {
           setting: 1,
         }],
@@ -41,13 +41,13 @@ describe('unit/getScore', function() {
     };
     var actual = getScore(differences);
 
-    expect(actual).to.equal(17);
+    expect(actual).to.equal(25);
   });
 
   it('returns minimal differences', function() {
     var differences = {
       rulesMissingFromLeft: [],
-      sharedRules: ['one'],
+      matchingRules: ['one'],
       rulesMissingFromRight: [],
       ruleDifferences: [],
     };
diff --git a/test/unit/test_render_differences.js b/test/unit/test_render_differences.js
index a86ad7d..db057ba 100644
--- a/test/unit/test_render_differences.js
+++ b/test/unit/test_render_differences.js
@@ -92,7 +92,7 @@ describe('unit/renderDifferences', function() {
       + '  _three\n'
       + '  _four\n'
       + '\n'
-      + 'Rules shared: None\n'
+      + 'Rules matching: None\n'
       + '\n'
       + 'Rules missing from left: 2\n'
       + '  +one\n'
@@ -144,7 +144,7 @@ describe('unit/renderDifferences', function() {
       + '\n'
       + 'Extends missing from right: None\n'
       + '\n'
-      + 'Rules shared: None\n'
+      + 'Rules matching: None\n'
       + '\n'
       + 'Rules missing from left: None\n'
       + '\n'