(せいしょく) These are both kind of scientific, non-sexy words for reproduction, but 生殖 means reproduction in a very narrow sense:as in ‘reproductive organs,’ or ‘the reproductive process’
(はんしょく) Breeding. Unlike the related term 生殖、繁殖 refers to the entire process of finding a mate, not just the physical act of insemination:Breeding grounds. Mating season. Farmers breeding livestock.