A "program" is a set of instructions for the computer. A program tells the computer how to do something. Some examples of programs are a game like Solitaire or Hearts, a "word processing" program for doing typing on, a "spreadsheet" program for doing calculations on, a genealogy program for recording and keeping track of your genealogy information, and a "paint" or "drawing" program for drawing pictures on.
"Data" is your information, your work. Some people think of data as "facts" (either written facts or numbers). This could be a letter you typed in, some addresses, some calculations, your tax information, a short story, genealogy information, a picture or photograph, etc. Data is what you put in the computer.
Everything put in the computer is either a program or data.
The program is your tool. The data is your work. You use the "program" to work on "your data."
