Hello! I wonder if there are any significal differences between them. I have one doll made from environmental resin and two heads made from urethane resin. I do not see any difference between them, to be honest, both of them are very smooth and nice. But I've heard that environmetal resin is a bit harder to paint. I've heard mixed opinions about imported resin, too. I know people who don't like French resin (because it yellows faster?) and some who really like Russian one. What is your experience? Do you have any opinion about them?