(By Johan van der Auwera, Nina Dobrushina, and Valentin Goussev): "Imperatives and hortatives both have to do with the expression of a wish of the speaker about a future state of affairs. In this respect they are like optatives (see Chapter 73), but in contrast to optatives, they convey an appeal to the addressee(s) to help make the future state of affairs true. In case the person in control of the desired state of affairs is the addressee or addressees, then we speak of an imperative. In any other case, we speak of a hortative."
Here the term "imperative" is restricted to 2nd person forms, whereas in the Grammaticon, "imperative" is used broadly to encompass all persons, i.e. including jussive and hortative forms.