Firstly, the computer scientists. There are possibly degrees of computer scientist and I believe that one is the general comp sci grad of which you speak, who generally builds systems themselves to see how they work, rarely use frameworks or boilerplates. They prefer to pick it apart themselves rather than just have it handed to them. They write less emergent code and more building-block code. Then there’s the second degree of computer scientist, the ones who don’t have a bachelor’s or master’s, but a doctorate in comp sci; the sort of person who has dedicated their lives to advancing the actual science of programming. They normally write huge research software like Neural-nets, genetic algorithms and other sorts of software that are purely experimental. Computer scientists also like writing their own languages and toolchains for them. They’re the sort of people who write esolangs like Brainfuck, and some more useful languages like Scala.

Now hackers. I certainly don’t mean those snot-nosed skiddies that you see in the headlines nowadays, breaking into poorly protected sites with simple SQL injections or brute-force attacks on FTP ports. I’m talking about the kind of people who write cracks and hacks for software that involves disassembling the native binaries and re-writing them in C for the hell of it, or the authors of extremely advanced malicious code like stuxnet. The sort of people who LIVE in assembly, know the entire x86 assembly instruction listing and exactly which one to use. Hackers like ASM, C, and Perl.