diff -ub file1 file2

$ diff -ub junk1 junk2
--- junk1       2012-02-24 16:49:06.953125000 -0800
+++ junk2       2012-02-24 16:49:05.718750000 -0800
@@ -1,5 +1,5 @@
 value1  value2   diff value3 value 4
 mango                 Total
-10       20      30    40     50
+15.6       20      30    40     50
 apple
-10       45.25      35     56    32
+12.3       45      35     56    32
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