Difference between “notes” and “original contributions” in journals I noticed that many, if not all, journals have two main type of papers: 


A short self-contained original research article of 10 pages or less, focusing on a particular result that does not provide enough material for a full-length contribution. 
Full-length original research article of more than 10 pages.


What is the actual difference between the two? What does does not provide enough material for a full-length contribution mean? 
In particular, I have a paper which is (or can be easily made) 10 pages. How should I know if it qualifies as a note or an original article?

Note that in most journals there are original contributions with less pages than some papers appearing as notes.

There are few other related questions, but none really answers (as far as I have checked) these issues. I am talking about applied maths,TCS.
I think this is one of those things that "you know it when you see it".

Very roughly, the distinction in my mind is that a full paper ("original contribution") should actually advance the state of the art in a specific, intentional way.  A note is more along of the lines of "I noticed this thing, it seems interesting and I think the community might like to know about it too."  Maybe it doesn't fit neatly into a larger research program, or its implications aren't immediately clear, but you think it is worth having in the permanent literature.

As you've observed, an original contribution can be short, if you have made a significant advance that just doesn't take that much space to write.  So the distinction isn't really about length per se.  Notes do tend to be short, mostly because the author may not want to spend a lot of time writing something massive (thus distracting from their real research program), and also because the simplicity or brevity of the result may be part of its appeal.  

I think the distinction becomes more clear with experience.  So if you are not sure about your paper, try showing it to someone more senior in your subfield and asking their opinion.