I went with the "green" drives because they were significantly cheaper at the time. I do know that the Synology firmware disables the "idle3" timer in Green drives that causes some problems with NAS operation, and that they fully support the green drives in RAID configurations. I'm sure there are other differences between the "red" and "green" lines that make the former better for NAS usage, but I've been pleased with the throughput on mine, FWIW.