Kexing is met-HGH which is 192 acids long. HGH (without the met) is 191. Jinotropin is HGH, or 191. Met-HGH appears to cause the same increases in effective GH, and the same increases in IGF as HGH at the same dose. Because Met-HGH is not natural, you will make antibodies to it. The antibodies do not seem to eat the met-HGH or make it less effective, and the antibodies go away after met-HGH is stopped. A few individuals have raging immune reactions to met-HGH, but most don't. met-HGH is significant cheaper than HGH, and for that reason is valuable to people who need this every day for years, or for insurance companies to lower their claims costs. Officially, met-HGH is just as good as HGH, but significantly cheaper.
Personally, I don't want antibodies to GH particles to be in my system. Also, met-HGH may cause more suppression of natural growth than HGH does, analogous to the way deca (19-nor-testosterone) causes more suppression than natural test does. And some body builders say kexing has more stinging and welts.
Personally, I prefer jins to kexing (I've never done kexing, just jin, but I mean that is my choice for myself). But you may want to try kexing once for the big savings and to see how it goes for you.