The 310-082 exam is the upgrade exam. It is for people who already have a SCWCD certification, but for version 1.3 or earlier.
“Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning.” - Rich Cook
If you are taking exam for the the first time you should go with the first one 081. If you have already taken for older version of 080 then you can upgrade with the 082. The Sun Certified Web Component Developer for the Java 2 Platform, Enterprise Edition 1.4 Upgrade certification exam is for candidates who have already successfully completed the Sun Certified Programmer for the Java 2 Platform (any edition) and Sun Certified Web Component Developer for the Java 2 Platform, Enterprise Edition (310-080) examinations.