Q. What is the difference between a literature review and a systematic review?

The difference between a literature review and a systematic review can vary a bit across disciplines, but for the most part, a stand alone article that is a literature review (every primary research article has a little lit. review at its beginning to give background to its research) looks at many - say 10 to 20 - primary research articles and summarizes and evaluates them so that when you read that one article, you really are finding out about many studies. You can find these in Solar, Medline, CINAHL, PsycINFO, etc.
 
A systematic review is more encompassing and has the purpose of looking at all the research published for a given topic and then also summarizing and evaluating, but with the added purpose of trying to give a best practice that all this research supports. These are best found in the Cochrane Library database and are known as the famous "Cochrane Review." You can also find these in the other databases and Cochrane Library does have other articles in there as well.