There are a couple of reasons for this.
Ceramic or metal burr.
With that isolated variable the ceramic had more sweetness for coffees roasted for espresso and the steel burrs clarity of flavor seemed better for espresso with coffees at production or non espresso roasts.
There s not really any difference when it comes to cleaning.
Ceramic burrs require a custom mold or tool to form them.
Ceramic burrs run a little cooler than steel burrs and there are some coffee experts who think the extra heat burns off some of the oils and impacts the flavor of the coffee.
Heat is an important factor when it comes to coffee grinder burrs because any extra heat impacts your coffee s flavor since it burns off some oils present on the beans.
The steel delivers very nice uniformity on coarser grinds any kind of drip while the ceramic generates a lot more fines in the coarser range.
Both can make fine grinds espresso very well.
For a couple of reasons.
In answer to your first question i do prefer the kyocera to the traditional box like grinders with steel burrs.
Currently most domestic burr grinders are made using ceramic instead of steel.
Quality of a burr comes much more from its machining tolerances and toothing design ceramic is typically used in very cheap and very expensive grinders.
If the burr is ceramic then the transfer is slower and more of the heat generated during the grind stays with the coffee.
Some people also have a preference for ceramic or metal alloy burrs.
No flat quality difference between metal and ceramic just different.
If the burr is made of steel then it absorbs the heat faster moving it away from the coffee.
However they will retain their original sharpness almost indefinitely.
So steel burrs are more effective at moving heat away from the coffee during the grinding process compared to ceramic ones.
First off ceramic burrs run a bit cooler compared to steel burrs or in other words they don t heat up as fast or retain heat as much as their metal counterparts.
Ceramic burrs are more brittle than steel so you could chip the ceramic burr if a very hard rock was hiding in the beans.
Ceramic is harder than steel which means the burrs will stay sharp for longer.
First their high strength blades are especially long lasting.
Baratza says that ceramic is good for 1000 1500 cups while steel is good for 500 1000.
Small stones and other objects can end up cracking them.
Ceramic burr are less thermally conductive than steel this means these burrs transfer less heat than steel burrs see below on heat.
The burr set is made from sharp stainless steel and it goes through medium roasted beans like a knife through butter.
Yet it s also more brittle.