Well, from what I can recall of the LSAT the CR sections are tougher than the CR sections on the GMAT. Also, just based on my memory, you are only alloted 35 minutes per section on the LSAT. The LSAT is designed in a way that many people are not able to complete all sections comfortably (another way it is difficult). The LSAT rewards fast readers far more than the GMAT does. Of course, that makes sense because as one of my law school professors told me, "the study of law is the study of language". GMAT definitely has a larger math/quantitative component to it.

Again, just going by what I recall, if you perform equally well on all sections of the test, you can miss about 2 per section to make the 99%, or about 4-5 per section to make the 90%.

Your improvement between the 2 sections should be encouraging. It's probably showing that your review helped, and that you are adapting to the style of questions on the LSAT. If the trend continued to be positive, I think that it will benefit you on the GMAT.

I can tell you from my own background that I missed, on average, 1-3 in CR sections on the LSAT (there are 2 per exam); and on average I miss 0-1 CR in the verbal section of the GMATprep & paper tests. On the GMATprep I'm missing on average 4-5 in the verbal sections, with most of the misses coming in SC. The LSAT is a great way to hone your skill in RC and CR for the GMAT.