To be published in a journal, an article must go through a process unique to academic journals: The Peer Review Process. No other type of publication goes through such a rigorous process.
What's different than a newspaper, magazine or most books?
Who reviews: Peers! As the name suggests, other experts in the same topic as the author are reviewing the article. They need deep knowledge of what is written.
Double Blind: Submissions are reviewed in a double blind process, which means neither the author nor the reviewer knows one another's identity.
Time: Submissions are almost always sent back for revisions - could be an overlooked citation or previous research, a question about ethics, a question about methodology. This back and forth can take months or years.
Cost: Subscriptions to most journals is much more than for a newspaper or magazine. Could be thousands of dollars a year for one journal subscription. Part of this goes toward the editorial services provided by journals.