Basically, diamond cuts faster and will impart a sharper feeling edge, whereas (as has been mentioned) chrome ox will leave a smooth comfortable edge. As far as steel type goes I don't think one is better than the other, but you should experiment to see what works best for you. I would recommend that you start off with diamond and if it feels a little harsh on your face you can always tame it with a few laps of chrome. The best of both worlds