diff --git a/app/helpers/pool_versions_helper.rb b/app/helpers/pool_versions_helper.rb
index 502000396..4c6fe01e8 100644
--- a/app/helpers/pool_versions_helper.rb
+++ b/app/helpers/pool_versions_helper.rb
@@ -21,6 +21,6 @@ module PoolVersionsHelper
 
   def pool_page_diff(pool_version, other_version)
     pattern = Regexp.new('(?:<.+?>)|(?:\w+)|(?:[ \t]+)|(?:\r?\n)|(?:.+?)')
-    DiffBuilder.new(other_version.description, pool_version.description, pattern).build
+    DiffBuilder.new(pool_version.description, other_version.description, pattern).build
   end
 end
diff --git a/app/logical/diff_builder.rb b/app/logical/diff_builder.rb
index deacc480d..75fe2c30b 100644
--- a/app/logical/diff_builder.rb
+++ b/app/logical/diff_builder.rb
@@ -12,7 +12,7 @@ class DiffBuilder
     otharr = that_text.scan(pattern)
 
     cbo = Diff::LCS::ContextDiffCallbacks.new
-    diffs = thisarr.diff(otharr, cbo)
+    diffs = otharr.diff(thisarr, cbo)
 
     escape_html = ->(str) {str.gsub(/&/, '&amp;').gsub(/</, '&lt;').gsub(/>/, '&gt;')}