Tutorial - Toughness and Wear Resistance Chart various Steels - CLICK TO VIEW
Toughness can be thought of as how a blade will handle shock, bending, torque forces and the like. There are official definitions but that is close enough.
Wear resistance can be thought of as to how long an edge will hold up cutting. There are specific tests for this. Generally, the higher the wear resistance, the harder it is to sharpen a blade.
Particle metallurgy is a much more complex way of making steel alloys.
"The CPM process begins with a homogeneous molten bath similar to conventional melting. Instead of being poured into ingots, the molten metal is forced through a small nozzle where high pressure gas bursts the liquid stream into a spray of tiny spherical droplets. These rapidly solidify and collect as powder particles in the bottom of the atomization tower. The powder is relatively spherical in shape and uniform in composition as each particle is essentially a micro-ingot which has solidified so rapidly that segregation has been suppressed. The carbides which precipitate during solidification are extremely fine due to the rapid cooling and the small size of the powder particles. The fine carbide size of CPM steel endures throughout mill processing and remains fine in the finished bar.
The powder is screened and loaded into steel containers which are then evacuated and sealed. The sealed containers are hot isostatically pressed at temperatures approximately the same as those used for forging. The extremely high pressure used consolidate the powder by bonding the individual particles into a fully dense compact. The resultant microstructure is homogeneous and fine grained and, in the high carbon grades, exhibits a uniform distribution of tiny carbides."
The process is more expensive, but even in alloys made from the same chemical make-up, like 154 CM and CPM 154, the particle metals finer carbides make for a superior knife blade.
Quote from RJ Martin discussing CPMS30v vs. CPM154:
"Both steels will make a very good knife. The CPM process will improve the toughness of a given alloy, because of the finer grain size and elimination of the larger carbides found in conventionally produced steels.
The Vanadium in CPMS30V does NOT produce large carbides. To the contrary, Vanadium Carbide is one of the smallest carbides that can be produced in steel.
Properly heat treated CPMS30V will out-perform CPM154CM in edge holding, because of the Vanadium carbides. The CPM154CM will be a little tougher and and little more corrosion resistant, particularly if it is polished out more than the CPMS30V, which is easy to do. Most issues related to corrosion are greatly affected by surface finish-the finer the finish, the less corrosion.
In a factory knife, you might see uncharacteristic "differences" between these steels, A CPM154CM blade at 60 Rockwell might outperform an S30V blade at Rc58 WRT edge holding, for example. Maybe.
Also, a lot of percieved difference in "hardness" has to do with edge thickness. Knives with thicker edges seem harder when sharpening because they have 4-8X more material at the edge that has to be removed during the sharpening process. So, they take longer to sharpen and seem "harder".
CPM154Cm would probably be a good choice if you want ease of sharpening and good overall performance."