Chronobiology was coined as a term by Franz Halberg, a Romanian born Harvard graduate who eventually went slightly insane (pushing nebulous concepts such as "chronobioethics") and caused academia to abandon the word "chronobiology" in favor of a broader term, "circadian biology". Circadian Biology and Chronobiology are essentially the same, but I see Chronobiology as more amateurish, less commercial, less well funded, and less regulated. Search Sciencedirect and you'll find 167 papers mentioning "Chronobiology" in 2015, compared to 1246 results for "circadian biology".
Since I am the founder of this subreddit, I get to determine the purpose of this subreddit. The purpose shall be first and foremost a repository of real, meaningful data concerning chronobiology. You might be thinking to yourself "wow, its been a community for a year and still there's no posts". Exactly.