RefWorks is a web-based citation management system. The system can:
The Write-N-Cite tool needs to be downloaded; unlike RefWorks which is web-based, WNC is located on your computer
Citation styles provide consistency in the documentation of references and in-text citations.
Once you get the hang of a style it is easier to write your references and read article references since the elements of the citation are written consistently.
Each discipline and many individual journals have their own styles, meaning that there are hundreds of styles.
The most commonly used styles are the ones developed for disciplines:
Humanities -- MLA (Modern Language Association)
History -- Chicago (University of Chicago Press)
Sciences and Social Sciences -- APA (American Psychological Association)
B.A., History. University of North Carolina, Chapel Hill. 1973.
M.S., Library Science. University of North Carolina, Chapel Hill. 1981.