Lower-ranked colleges often have more formal homework and more graded assignments, and more rigorous grading. Higher-end colleges are typically easier and impose less busy-work. But for engineering and hard-science, all bets are off and it's tough anywhere decent.
I don't think this is necessarily true at all. I do think there is some truth that lower ranked universities in certain subjects may assign more homework and grade it more carefully, but only because they expect a lower level of independence from the students. At my SLAC, I had a couple of classes where homework was optional--we were assigned it for practice, but it was our responsibility to learn the material. I also had several classes that didn't assign homework, but had extremely difficult exams, and if I didn't put the work into it, then failing was the consequence. At places with a less independent and motivated student body, sometimes you need to collect and grade homework to force kids to study/practice.