More than likely the timing of the two modules are differnt. Just becuase you purchased a memory module that is the same size and clock rate doesn't mean that their timings are the same. Without knowing the exactly module type of the Micron, I couldn't tell if your module was a 11-11-11, 9-9-9, or 7-7-7. But your Corsair module is definitely 9-9-9-24
When purchasing memory you need to take the timings into consideration as well (though you probably won't really see a significant change between the different settings).
You should also realize that you're loking at different slots as well. Slot one will have JDEC #'s 1-3 and Slot two will have JDEC #'s 4-7. So your original module didn't have 7 timings.
Note: smaller timing are considered better if I remember correctly.