R is a programming language that can be used to represent data.
RStudio is the interface of the programming language R, the program you use to enter the data to receive a result produced in R.
R packages are like apps on a phone. They are programs you can install into RStudio to make the programming easier, or for certain tasks. Hint: Type your answer in bold.
Note: For help with RMarkdown syntax, go Help > Cheatsheets > R Markdown Reference Guide.