Getting down to the modules themselves, both kits are Dual Channel ready. If you don't know what that means, simply put they are two identical modules designed to run on both Intel and AMD platforms (not so much AMD with DDR3 yet) which have a 128-bit memory interface allowing for a doubling of the bandwidth between the CPU and memory. The DDR2 kit we were supplied was a 4GB kit and our DDR3 was a 2GB kit.
Both memory modules used the exact same heatsink design to cool their respective modules.
However, to avoid confusion the DDR2 kit's heatspreaders were coloured blue and the DDR3 black. Both modules are 240-pin interface with the board, but this is where things change. DDR3 is not electrically compatible with DDR2. DDR3 runs at 1.5v default where DDR2 runs at a higher 1.8v, so if you did manage to stick a DDR3 module into a DDR2 board, chances are you will fry it, especially since the pin configuration is different.
Getting down to the specifics of the modules, our DDR2 kit came with 2x 2GB modules for a total of 4GB. These modules are designed to run PC2-8000 or 1000 MHz with timings of 5-5-5-15 at either 2.0 or 2.1v, which is pretty high really; but when you consider DDR2 is only rated at an official 800 MHz it's clear to see why such loose timings are needed in this case.
The DDR3 kit on the other hand is a 2GB kit with 2x 1GB modules designed to run at PC3-12800 or 1600 MHz using timings of 7-7-7-18 and a max of 1.9v supported, which isn't too high for these particular modules. These aren't rated for Intel XMP so X38 users don't get any special treatment here, but that's not a great loss.
PRICING: You can find products similar to this one for sale below.
United States: Find other tech and computer products like this over at Amazon's website.
Australia: Find other tech and computer products like this over at PLE Computer's website.
Canada: Find other tech and computer products like this over at Amazon Canada's website.