Loose speech is crude or lewd speech, such as talking about how women (or men) behave, or gossiping, and so forth.
Lying means not telling the truth.
Harsh speech refers to scolding people, which creates mouth karma.
Divisive speech means being double-tongued in the sense that one back-bites and causes schisms. Such a person tells A about B and then B about A, trying to split them up. That is how divisive speech works.