My #1 recommendation- Get her the computer that she wants to use.
Typically, if you're an engineering/science/math major, most of your programs will be PC related. But, with the software available, it's ridiculously easy to run Windows software emulators on an Apple. I did this over 8 years ago as an Aerospace Engineering major at UCLA, I used an Apple computer my entire college career and never had any issues running the software I needed to run at home. And the software I used is archaic compared to now, my Apple desktop running a DOS emulator and then my engineering software was still more stable than the vast majority of my buddy's PC's. The really big ugly software has to be accessed from a campus computer lab anyway, and is too expensive to even think about buying yourself.
If she's a graphic design/art major, get an Apple. They don't make any Apple OS emulators to run on a PC, so, if you need an Apple, it has to be an Apple.
And any other major won't matter at all. So, it really comes down to what she wants and is comfortable using.
A big question that you do need to answer is, Does she really need a laptop? Laptops are usually almost twice as expensive as a comparable desktop, and are more likely to be damaged. Everyone I knew had a computer, but I, and a lot of others, made due with just a desktop. For me that's probably even a more important question than which kind to get.