in a limited government the government is limited by law
in a unlimited government the law sets no limits on the actions of a government
tyranny can result in an abuse of power such as the abuse military power against its citizens.
When there is a normal democratic limited government the government can not use force like police or military against protesters or other sorts of opposition. In an unlimited government or a tyranny the government can enforce its will on its citizens and almost nothing can stop it except an uprising or something similar.
