Fortunately a lot of software these days is web-based, but if you have to install something on your machine and run it there is a chance that your chromebook won't be able to do it. It can be amazingly frustrating (for example) just to play certain types of video files on a chromebook.
Since I knew this kid would be actually needing to run stuff I opted to not risk it and just went with the windows laptop. It has the added benefit of me being to easily help her if she runs into problems with it. If my kids and I were more familiar with macs I probably would have gone with an old macbook or something.