A scientific paper is what we call a publication in a science journal*. It's an explanation of the methods, results and analysis from a particular project undertaken by scientists. Think of it as the same as your lab reports, but more advanced.
Those are probably the most prestigious general science journals. If your work is published in those then you're doing pretty well. From what I remember both of them have a strict four page limit on articles so the information in them skips most of the background information and is very concise so as a result can be hard to follow.