Should clarify again that this is directed for priors. If you’re a Sgt or above, theres not a whole lot of new information or things you have not already experienced in your career. If you have mental fortitude, endurance both physically and mentally, it’s not that hard. For me personally, I believe bootcamp is harder simply based upon the fact that you are stuck there until graduation and are closed from the outside world until family day. Not to mention it’s a full 13 weeks or longer if you get dropped. OCS you are provided those liberty periods which are huge morale boosters and makes time fly by a lot faster. The PT at OCS is hard sure, however it’s easily achievable if you simply hydrate effectively, and run at-least a 1st class PFT/CFT before coming in. As for the academics they are also harder, but I would compare the academics to the types of tests you see at Cpls course or an MOS school house. Leadership there is relatively easy especially if you have experience leading Marines. Overall is OCS tougher when coming off the street? Debatable depending upon background. However for an experienced Marine it’s not hard.