The Ortofon 2M Bronze is an upgrade over the 2M Blue. It has an upgraded lower output motor and a nude fine-line stylus. The 2M Bronze will be a little less forgiving than the 2M Blue, so try to use it on a little nicer tonearm with better bearings.
The 2M Bronze is a little more refined and gentle sounding than the 2M Blue - it gets rid of some of the slightly brash upper range glare. It's not quite as fast and gives up some resolution to its bigger brother the 2M Black , but rewards with a little more forgiving setup - we'd recommend putting one of these on an older or midrange table over the 2M Black. Excellent cartridge. If you love your 2M Blue, this is an excellent upgrade path.