Hi,
Thanks to Sylvain, I saw on an french task list (1) that a clear explanation of the difference between a bitmap/raster file and a vector one was wanted for the website. I also read a part of the conversation on the bug report page (2) (not everything as the discussion is quite long :) ).
If it's still on the todo list, I just wanted to mention that the Mapschool page (3) has a short paragraph that explains the difference between both. As it's licenced under CC0, it could be partly recycled for the Inkscape website.
I'm available to help on this topic, but as I don't really know where to start, a quick heads-up would be appreciated!