The Crucial M4 (Micron C400) is the successor to the C300 we saw last year and was one of the first few 6Gbps SSD available. Price ranges heavily for the M4, going from mid $100s to almost as much as $1,000 for the high-end, 512GB model.
Uh.. so long story short, the Micron RealSSD C400 is basically the brand new Crucial M4 (also listed on same page as you can see above). Same spec, same deal, heck.. its from the same manufacture (Crucial is Micron's consumer arm).
Slightly steep price on this SSD when compare to previous gen, but come on, you're getting 415 MB/s read, 260 MB/s write, and stupid fast random 4K read/write. The naming convention may be confusing, especially consider the previous RealSSD C300 was released under the Crucial brand name, but who knows what those suits at tech companies are thinking. Because the drives are the same deal, we currently recommend the slightly cheaper Micron version as the coupon nets you more savings.