Ram form factors are standardized, though typically there's two common standards per ram standard - SODIMM for laptops and small form factor systems, and regular ram.
Looking up the model numbers they're both SODIMM, though the former is 'regular' ram while the second one is low voltage ram, and premium branded (They slap a heat spreader on this).
My reasonably educated guess is that the Product and Item Dimensions are for shipping and are the size of the packaging. The regular ram probably comes in a clamshell, and the other ram comes in a box. Looking up both models confirms they are SODIMM.
That said, one of these ram types is incorrect depending on the system. Some systems will only work with low voltage ram. Mixing low and high voltage ram may work if the system supports it, though the low voltage ram will be running at a higher voltage, negating many of the advantages of it.
A good rule of thumb is to try to match the ram you have.