(A comment by me on an FSP post)
...From discussions with academics in humanities, the demands, pressures, and everyday lives of humanities and science academics are very different. For one thing, it seems much more difficult to get a paying job in the humanities (as a grad student, as a professor, or as anything else.)
The student-professor relationship also seems very different. Students who work as research assistants in humanities seem to get paid, but get no credit on publications for which they assist? And students' research may have very, very little to do with their advisors' research. In contrast, Ph.D. advisors in the sciences seem to have huge responsibility to their students, often providing funding, lab space and equipment, the big idea behind the projects, and various degrees of involvement in their students' research process. All that responsibility is in exchange for co-authorship on publications, which seems to be the main determining factor on tenure decisions for all academics.
It seems like science professors are more managers and project leaders, while humanities professors continue more directly doing research and writing. That difference is much larger than just the disparity of the fields.
And there's also the difference that in science, researchers have to conceive of an idea that is interesting and not already published, design and build instrumentation to test said idea, acquire data (which may or may not provide interestingly interpretable results, and then analyze, interpret and publish said results. In the humanities, researchers get to skip right from conceive of an idea to the analysis. And they never have to worry that it just won't work. Effing science.