One of the most important differences between distributions of Linux is, is the availability of packages you can install via the standard package-management system.
For example, for biomedical work, there is a very useful range of free packages you can just install on Debian or Raspbian with apt-get, thanks to the software-packaging efforts of the Debian Med project.
This availability of relevant packages is one of the things which makes the Raspberry Pi (with Raspbian) suitable for computational biology education.
Not everyone has focused on Debian - some other subject areas may be better represented in the package repositories of other Linux distributions.
Depending on your planned use of the system, this may not matter at all. I imagine the 'standard' GNU software is available in Linux packages for most/all Linux distributions.
Daniel Barker http://biology.st-andrews.ac.uk/staff/db60