OK I'm not sure what the difference between these two tests are. From what I have gathered you plug into the park plug port and then turn the engine over a few times to see what each cylinder's leak down and/or compression is. What's the difference between these two test? how much to buy the components to do these tests and what info will they give me.

So I want to verify that my engine is running in tip top shape. Which test do I need?

Thanks for the help,
Mike