FWIW, over Thanksgiving weekend I saw two 2017 HS grads (a PAC12 player and an Ivy player, home for the long weekend) at my son's baseball game. I asked them a version of the OP's question: "Is college baseball super intense?" The answer I got [from the PAC12 player] were that the lifting is way more intense. Not even close. The baseball work (at least in the fall) was described by both as not more intense [perhaps due to NCAA limits on fall practices?]. Maybe that will change in the spring?
College schoolwork was described [by the Ivy player] as a lot less busywork but very demanding [which makes sense given that HS students are in the classroom 30+ hours per week, whereas college students are in the classroom about 15]. And both kids said the other big bonus was no commuting time [my son's HS has quite a bit of that].