What is meant by "Body text" and how does it differ from "Paragraph"?

For those who see this and don't know what you mean, this is a Thunderbird option: Menu: Tools: Options: Composition section: General tab It has a checkbox option for "Use Paragraph format instead of Body Text by default". Theoretically, when using Paragraph format, when you are composing an e-mail and press the Enter key, you get an extra line of empty space between the last paragraph and the new paragraph. It doesn't work for me, though (Windows 10). I put a checkmark in the box, and nothing changed for composing an e-mail. I restarted Thunderbird several times, changing the option back and forth, but I always get the normal "Body Text" format.