Well as of right now, Chadsvideos.com only has the Chemistry section, whereas Coursesaver.com has both the ochem and chemistry sections. Also, after watching some videos form both sets, the newer Chadsvideos.com content IS NOT DAT focused. The videos from coursesaver are obviously older (2012) but i definitely found it more useful to study those and learn only the things that applied than to watch the newer videos and just have a lot of general chemistry knowledge. unlike the Bio section, Chemistry isn't breadth over depth, there's some things you should know and some you shouldn't waste your time with. An example would be when learning about Molar solubility, the newer videos go really in depth and give you some of the more complicated questions, which are good to know. But the older videos get straight to the point and say specifically "DAT students you need to know this" or "You don't need this for the DAT don't worry about it." I just prefer the older ones a lot more, but that's just my personal opinion.