When you give a command, you use a specific tonality. Statements end with a flat tone at the end. Questions end with a rising tone. Commands end with a slightly falling tone. The severity and urgency of the command is related to the tone. If there is a monster standing behind your friend, you would say “Run!” with seriousness and urgency.

On the other hand, if you were reading instructions from a recipe to your friend, you would say, “add two cups of milk” with a command tone, but it would be a very polite command tone.