Q: What is the difference between a narrative review and a descriptive review?

At a lay level, they seem to be used interchangeably. However, at the academic/scientific level, a ‘narrative review’ is actually a literature review and a ‘descriptive review’ is a systematic review.

A literature review, as the name suggests, is a review of existing literature around a particular topic. It involves discussing and possibly even critiquing existing studies. Note that this is a stand-alone paper, and therefore, different from the literature review that is done as a part of a primary research paper. Here, you discuss each study: what it says, where it falters, and so on. In the review that is a part of the main paper, you merely cite the key findings of papers relevant to your study. A (stand-alone) literature review also differs in how it is organized or structured: thematically, chronologically, or alphabetically. [Learn about the difference between the two kinds of literature review in this piece: How to write the literature review of your research paper]

A systematic review is a more rigorous review of existing literature. There is extensive synthesizing done of the various studies – how the findings from one study pertain to those from another – which is typically not done in a literature review. However, more importantly, a systematic review is done around a clearly formulated research question. A literature review is simply done around curated relevant literature.

To answer your second query, the differences between the two may dissolve when you have a very sophisticated literature review that approximates a systematic review. However, from an academic perspective, there is a clear demarcation between them. To know more about the two types of review and the differences between them, you may go through the following resources:

• Secondary research – the basics of narrative reviews, systematic reviews, and meta-analysis
• A young researcher's guide to writing a literature review
• A young researcher's guide to a systematic review

Additionally, you may look up papers online. They are typically indicated by the type of review mentioned after the colon (:), which features the topic of the study before it. A systematic review is titled ‘a systematic review.’ A literature review is often simply titled ‘a review.' Here are examples for each: Literature review and Systematic review

Hope that helps. And all the best for your review, in case you are planning one. In which case, you may also learn about how our Literature Search service can help power your review paper.