These words are derived from an Old English word meaning "desire" and "pleasure," but they have different meanings and applications in modern usage. Lustful means "full of greed": "This politician is lustful for power." Lustful also means "lecherous," "having lewd desires," "sexually desirous": "Persons who like X-rated films are usually lustful." "Young girls often claim to fear lustful males." Lusty means "full of vigor," "hearty," "robust," "sturdy," "strong": "This is a lusty young athlete." "He has a lusty attitude toward life." A lusty person may be lustful, but not necessarily. A lustful person may not be lusty at all.
Dictionary of problem words and expressions. Harry Shaw. 1975.