david weaver
...no practical difference between the two unless either is being asked to do more than it should.

What william and steve mentioned about chrome ox (william being far enough along to just say that it works and it's a settled issue for him) are about what you'd want to do with anything that small in particle size.

It wouldn't really make any difference if it was 0.25 micron diamonds, half micron chrome ox (or 0.3) or small alumina. In my opinion, the choice of the backer and how it's being used is more important than the media.

Chrome ox will be available because there is an economic subsidy from another hobby - shavers. Shavers will spend quite a bit experimenting with getting a good edge because it's an easy thing to do, but elusive for most beginners. Chrome ox has a nice quality and yields a good shave, making a difference that you can feel vs. something like 1/2 micron diamond.

The issue with all of it is learning to use it in context, and then sticking with the process and not mixing and matching different things without accounting for their differences (for example, people looking at grit charts and wanting to replace an 800 stone with an oilstone of "similar grit").

Iwasaki was selling razors that he finished with 1 micron diamonds, but after he used a good natural stone properly - the diamonds were used to "soften the edge" in his terms, and on an ultra soft backer. To put a razor on one micron diamonds as a final step on even soft leather would've been a no-no, but he used something like a soft felt cloth.

Long story short, no practical difference with any of it (except for me, the abrasives with the color as an integral part of the abrasive makes for a nice visual - you're never guessing at how much you have).