diff --git a/gui/fitDiffFrame.py b/gui/fitDiffFrame.py
index 865d73b8c..2e2c45a3c 100644
--- a/gui/fitDiffFrame.py
+++ b/gui/fitDiffFrame.py
@@ -22,6 +22,7 @@
 import wx
 from collections import Counter
 
+from eos.const import FittingSlot
 from service.fit import Fit as svcFit
 from service.port.eft import exportEft, importEft, _importPrepare
 from service.const import PortEftOptions
@@ -189,13 +190,33 @@ class FitDiffFrame(wx.Frame):
         fit1_modules = self.getModuleCounts(fit1)
         fit2_modules = self.getModuleCounts(fit2)
 
-        # Diff modules - only show items needed to add
-        all_module_types = set(fit1_modules.keys()) | set(fit2_modules.keys())
-        for module_type in sorted(all_module_types):
-            count1 = fit1_modules.get(module_type, 0)
-            count2 = fit2_modules.get(module_type, 0)
-            if count2 > count1:
-                diffLines.append(f"{module_type} {count2 - count1}")
+        # Slot order
+        slotOrder = [
+            FittingSlot.HIGH,
+            FittingSlot.MED,
+            FittingSlot.LOW,
+            FittingSlot.RIG,
+            FittingSlot.SUBSYSTEM,
+            FittingSlot.SERVICE,
+        ]
+
+        # Diff modules by slot - only show items needed to add
+        for slot in slotOrder:
+            fit1_slot_modules = fit1_modules.get(slot, Counter())
+            fit2_slot_modules = fit2_modules.get(slot, Counter())
+            
+            all_module_types = set(fit1_slot_modules.keys()) | set(fit2_slot_modules.keys())
+            slot_diff_lines = []
+            for module_type in sorted(all_module_types):
+                count1 = fit1_slot_modules.get(module_type, 0)
+                count2 = fit2_slot_modules.get(module_type, 0)
+                if count2 > count1:
+                    slot_diff_lines.append(f"{module_type} {count2 - count1}")
+            
+            if slot_diff_lines:
+                if diffLines:
+                    diffLines.append("")
+                diffLines.extend(slot_diff_lines)
 
         # Get drone counts
         fit1_drones = self.getDroneCounts(fit1)
@@ -247,18 +268,22 @@ class FitDiffFrame(wx.Frame):
         return diffLines
 
     def getModuleCounts(self, fit):
-        """Get a counter of module types for a fit.
+        """Get a counter of module types for a fit, grouped by slot type.
 
+        Returns a dict mapping FittingSlot -> Counter of module names.
         Position doesn't matter, just counts by module name.
         """
-        counts = Counter()
+        counts_by_slot = {}
         for module in fit.modules:
             if module.isEmpty:
                 continue
+            slot = module.slot
+            if slot not in counts_by_slot:
+                counts_by_slot[slot] = Counter()
             # Use item type name for comparison
             name = module.item.typeName if module.item else ""
-            counts[name] += 1
-        return counts
+            counts_by_slot[slot][name] += 1
+        return counts_by_slot
 
     def getDroneCounts(self, fit):
         """Get a counter of drone types for a fit."""