"Looters" are Rand's depiction of bureaucrats and government officials, who confiscate others' earnings by the implicit threat of force ("at the point of a gun").
"Moochers" are Rand's depiction of those unable to produce value themselves, who demand others' earnings on behalf of the needy, but resent the talented upon whom they depend, and appeal to "moral right" while enabling the "lawful" seizure by governments.