One of the best indications that the citation you're looking at is for a magazine or journal article is the presence of a volume and issue number:

Note that issues such as whether it has advertisements and whether it is visually stimulating are easy to determine in the print version of the source, but much less apparent in the electronic versions within databases. In these cases, rely on the author credentials and references given. Also, see the "accuracy/substance" tab for determining whether or not it is refereed.

Most of your research should come from scholarly journals, rather than magazines. There are times, however, when magazines are OK to consult, particularly if you are trying to determine how an issue is presented to the general public. If in doubt, you should clarify this with your professor.