What exactly is the difference between....

[rbmcmjr]

You are correct. The CPM part is the process by which the steel is alloyed/made.

As far as CPM-154CM, that does not exist. It's a typo made across the board on specs on knives. It's either 154CM or CPM-154.

Crucible brought it upon themselves with questionable naming practices when they introduced it. From a six-year old thread in Shop Talk:

I had a visit from Kerrie Kengor,the rep from Crucible Steel Monday.Nice lady.She is going to be getting some technical info for me on the CPM 154.What she had so far from the lab boys is that it works and Heat Treats the same as the old stuff.The polish is better,and as far as knives go,the edge should be better.
We discussed the nomenclature,which is still confusing.Sometimes it is labeled CPM154CM others CPM154.The older,non-particle process ,steel is still 154CM.She thinks they will start using CPM154 as the new name.
I am working with Crucible on a test project to do a comparison on O-1 vs CPM154 vs CPM125V.(cheap and easy vs more expensive,but better vs way pricey,but superb) The results will be released in an article for one of the magazines,and ,of course,here on the BF.
Stacy

 

[RevDevil]

Interesting info, thanks for the link.