Difference between article and letter in Nature As I was reading today an article from Nature I was wondering: Does anybody know what's the difference between article and letter in the Nature Journal?
The blog of Nature points out the following:

Articles are original reports whose conclusions represent a substantial advance in understanding of an important problem and have immediate, far-reaching implications.
Letters are short reports of original research focused on an outstanding finding whose importance means that it will be of interest to scientists in other fields.

Source:
http://blogs.nature.com/nautilus/2009/12/difference_between_nature_arti.html
They have a difference in the allowed length, and the importance of the results. Articles are longer and supposed to have "far-reaching implications". In other words, no chance to get an article unless you revealed that the moon is actually made of cheese or the like.

Letters are shorter, yet still very prestigious.