It's a totally different manufacturer. The v2 sensors were made by CentraLite. The new ones are made by the obviously equally well-known company "iMagic by Great Star." 
There are also additional non-cosmetic differences, including a larger battery (CR123A vs. CR2) and range/field-of-view differences I summarized in another post in this thread: New Iris Motion Sensor? Version / Generation 3?
Everyone I've seen say anything about them so far has said they work well, though they haven't been out long enough to gauge long-term reliability.
