adam.keith
31
No difference--both are 14060M
In 2007, Rolex "upgraded" the 14060M to the COSC-certified designation---meaning, that currently the 4-line COSC dial is what you will be more likely to find in dealer's cases, although there will be some non-COSC 14060Ms still floating around (as well as plenty on the pre-owned market).
Both are equally good watches, and which looks better...is of course, a matter of personal opinion. Devil's Advocate from a collectors perspective might be that the COSC 14060Ms may be more desirable in the future, as the production time will have been much less (from late 2007 to present) versus the many years that non-COSC 14060 and 14060Ms were produced, assuming that the 14060M is discontinued or upgraded, as has been recently done with the 16610 to the fancier 116610.
Hope this helps--and if you buy what smiles at you, you will have a great timepiece to enjoy 
Best,
Adam
Intending to buy a Submariner
By: MWL : July 5th, 2010-07:23
Hi there, This is my first post here, but I've been lurking around for a while reading some excellent reviews etc, and have as such been influenced into getting myself a submariner, as my Reverso Squadra is getting quite beaten up being my day-to-day watc...
Agree with Velociphile
By: adam.keith : July 5th, 2010-17:01
Get the current 14060M. Since you (as I do) prefer the beautiful clean dial of the non-date Submariner, and want something unquestionably robust you can wear all the time that can "take a hit" and shrug it off, this reference is your clear choice for a go...
Sounds good
By: MWL : July 6th, 2010-00:41
Thanks for the quick response. Ill be going on a hunt when I get back to Hong Kong, so Ill keep those numbers in mind. As to the COSC or non-COSC, is there any difference in reference number? Thanks, Maxi
14060...
By: Slugo : July 10th, 2010-16:40
IMO the no-date Sub is definitely the way to fly. Here's a pic of my first A-series 14060, followed by my recently purchased COSC 14060M. I love them both, but prefer the older version because of its simple design and cleanliness... 14060... 14060M COSC.....