difference between research paper and review article
There is no difference between the terms 'paper' and 'article'. A research paper is one where an original study has been performed. A review paper may be either a narrative review, a systematic review or a meta-analysis. A narrative review is like a book chapter: it explains a topic in detail based on previously published research.
I. Research Question(s) / Purpose of the article. Every article has a purpose or a main research question to guide it. Sometimes this is formally stated while other times the reader must glean this information. You can find this information in the article's Introduction and, sometimes, the abstract.