I'm not sure, but I had the chance to compare them... sort of. please note - I suspect that my microns are counterfeit/copies, (but they work pretty well for those) so I've never really tried REAL microns I suppose. Well, maybe not, because I think one or two are real microns...
I feel the microns run smoother, and although they sort of make the same lines, I feel the Staedtler are sort of.. scratchy on the paper. apart from that... they do seem sorta similar.