Dear honorable colleagues,

Let me answer this question by copying some of what I have mentioned in my last article:

"There is a clear and distinguishable variance between both theorizing that is largely based on the theoretical-academic world and the implementation that is conducted upon real-world cases. An analogy with this, there may be some considerable gaps between the theories and their corresponding real-world implementation. This mismatch between both of them is, of course, caused by the fact that some metaheuristics are relying on just theoretical or abstract possibilities without applying them viably with the real-world applications or that some of them have been tested and then evaluated using only low-to-mid-range data without exposing them hard on large-range data. Close related to this, a considerable fraction of these researches have been originally initiated for only research purposes without being for real-life applications.

More importantly, some metaheuristics are just carried out inside research labs where some of them have been constructed based on hypothetical projections with only an academic or theoretical vision that may be far away from the factual situations. That is, carrying out lab-problems merely without being exposed to diverse real and hard tests is subject to guesswork and experimentation may lead to unexpected results. On top of all that, nearly the majority of these labs are subject to some financial constraints with rare to no external support available. Inevitably, this lack of certainty may rarely lead to unfaithful decisions and hence far-reaching problems."

The theoretical review looks at existing theories (concepts or whole), their relationships, extend the theories have been studied and the establishment of new hypotheses. While empirical literature review explores past studies in view of attempting to answer specific research questions.

Empirical reviews are based on experiments while theoretical reviews focus on and investigate theories already exist. An empirical literature review refers to systematic literature reviews with RCTs while theoretical reviews could include any other types of studies (experimental, non-experimental).

If both empirical and other review of literature are related, no problem to talk about both of them together in same review. However, if the empirical has a lot of information to gather and discuss, it could be treated separately, although they are less to be reviewed alone. Thanks to your question. Cheers.

A theoretical literature review is included in pretty much every research paper you will see. Before a researcher can acceptably write about their research, they need to establish it within existing theory. So, essentially, before we discuss our method and research questions, we describe the kind of work that has been done before and show how the variables we intend to examine are established in the theories and frameworks of our research area.

An empirical literature review is more commonly called a systematic literature review and it examines past empirical studies to answer a particular research question. The empirical studies we examine are usually random controlled trials (RCTs). Because most RCTs have low sampling sizes, we can often see mixed results from study to study and we hope to provide more clarity by combining the results of all existing studies.

These two things are similar because they require an examination of past paper in the subject. They differ in that the empirical literature review tends to answer a very specific empirical question and will use data analysis to come to a clear response. The theoretical literature review is really more for setting up the context for your own study. In fact, systematic empirical reviews will also include a theoretical review to set up the reasons for studying their particular research question.

For further information, please check

https://www.quora.com/What-is-the-difference-between-theoretical-and-empirical-literary-reviews/answers/178970986?ch=10&share=82e16ad0&srid=urTEv1

Dear honorable colleagues,

Let me answer this question by copying some of what I have mentioned in my last article:

"There is a clear and distinguishable variance between both theorizing that is largely based on the theoretical-academic world and the implementation that is conducted upon real-world cases. An analogy with this, there may be some considerable gaps between the theories and their corresponding real-world implementation. This mismatch between both of them is, of course, caused by the fact that some metaheuristics are relying on just theoretical or abstract possibilities without applying them viably with the real-world applications or that some of them have been tested and then evaluated using only low-to-mid-range data without exposing them hard on large-range data. Close related to this, a considerable fraction of these researches have been originally initiated for only research purposes without being for real-life applications.

More importantly, some metaheuristics are just carried out inside research labs where some of them have been constructed based on hypothetical projections with only an academic or theoretical vision that may be far away from the factual situations. That is, carrying out lab-problems merely without being exposed to diverse real and hard tests is subject to guesswork and experimentation may lead to unexpected results. On top of all that, nearly the majority of these labs are subject to some financial constraints with rare to no external support available. Inevitably, this lack of certainty may rarely lead to unfaithful decisions and hence far-reaching problems."

The integrated literature review (ILR) is the type of literature review that is not either theoretical literature review or empirical literature review but integrating both. Maybe it could serve as one way to fill the gap between 'theoretical-academic world' and 'real-world cases' that Nidhal Kamel Taha El-Omari mentioned of? Anyway, from the day I started to learn the ILR method, I found it could be very powerful!

Literature review reflect the scan of related previous significant studies