I know the main difference is that with a Neuroscience and Behavior degree, you can still do something if not admitted into medical school but does any one of these prepare you better for MCATs and med school than the other? Is one of them easier than the other?
The best way to estimate what major would better fit you, would be to look at the different required classes for each.
First off I want you to understand that the Neuroscience and Behavior major has a premed concentration- in other words it is designed for people who want to take the have a normal Neuroscience and Behavior major, but fulfilling pre-med requirements through electives and additional classes. This program is done through the college of arts and letters and will give you a BA, not a BS. here is the link to the normal schedule with someone with this major; see if you like it:: http://psychology.nd.edu/assets/157112/link_4.pdf
SCPP on the other hand, is a major the college of science and will give you a BA. It is obviously more general than the neuroscience one. The sample schedule is here:: http://science.nd.edu/undergraduate/sample-curricula/preprofessional-studies-sample-curriculum/
In terms of readiness for the mcat, both basically have the same core requirements and will prepare you similarly, so I would say your fine going either way. But, do note that if you majored in biological sciences, which also fulfills premed requirements, you would take more bio classes and likely be more prepared for the mcat.
Since your looking to double major in Chinese (im psychic), I would say you should go for the neuroscience track, as it is will prepare you well for the mcat, while still letting you take classes you are interested in (just my 2 cents). Your second semester of your freshmen year will be very very very hard, as that is when orgo1 and calc B are taken (notoriously hard), but you will manage if you try really hard. Lastly, I really hope your doing premed because your interested in medicine and not just doing this to make your parents happy, because, if that is the case, this will be hard to get past.
That being said I think I left you enough resources and advice. I leave you with this- pick the major/premed track that suites your interests and is what you like to do! Dont do something because one is easier than the other, but rather do the one you like more and the rest will fall into place.