I would suggest Django over RoR; RoR contains more magic (but RoR seems to offer more convenience for someone experienced with RoR since it is based on convention vs configuration.) Also, I have heard that Rails changes very fastly sometimes, so you may have difficulty catching up if you are a student (but at the same time, it has a livelier community, so that might be a plus -- check out http://rubyweekly.com/ ).

With Django, the core structure is simpler to understand, and you may continue working on your site after a few week's break easily. This is a little bit like the difference bt. Python and Ruby/Perl; I find Ruby/Perl more flexible (there is more than one way to do it), Python to be more strict (there is usually a single best way).

To sum up, I don't think it would make a difference if you were a full time developer working on the project every day, but for a student, occasionally working on a project, Django would be easier to get accustomed to, after not working on the project for a given time.

PS: I suggest you to take a look at Flask (Python) or Sinatra (Ruby) too; they might be easier to start with. Your experience with Flask would help with Django, too (or vice versa).