Both of these tools are useful when you are working on a research project and need to find additional resources. They are especially helpful when you have found a couple of articles that are exactly what you are looking for in your research. These two tools can help you identify more resources that were either cited by a particular article (or where the article was cited) or find articles that are similar and related to the one that you searched for in Google Scholar.
The "Cited By" feature
You can use Google Scholar to see what researchers and articles have cited a particular article or author.
The "Related articles" feature
This feature allows you to click on related articles and Google Scholar will look for articles that are written on a simlar topic as the one that you have found.
How do I use the features?
After you search something at the bottom of each description there is a clickable link that says "cited by" and has a number beside it that is how many people have cited that article/book.