They're both DDR2 boards.
I believe the more expensive one has higher quality voltage regulation circuitry.
With any luck, either pscout, or 3.0charlie will jump in here, as I know they both did a fair bit of research between the two boards... :)
There was some discussion of the two boards in this thread....
http://www.hardwarecanucks.com/intel...-my-e6420.html
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