Not everything in a peer-reviewed journal is peer reviewed. Often these journals will contain editorials, book reviews, news articles, and opinion columns that do not go through peer review.
Many databases will allow you to limit your results to only peer-reviewed articles. Look for a box that says limit to peer-reviewed journals, scholarly articles, academic journals, or similar language.
Note: These are usually reliable, but some articles that are not peer reviewed may still appear, especially if they are in a peer-reviewed journal but not themselves peer-reviewed. Always do your own evaluation.