A lady is a Woman belonging to the upper class. Ladies are generally rich or Middle class. Ladies wear expensive clothes. Ladies tend to look down on poorer people. In the 21st Century it's acceptable in some circles for a lady to do paid Work provided she's confident, self assured, well mannered and the like. 
Lady of leisure
Some are exploited by rich gentlemen who are their fathers, other relatives, their husbands.
There should also be a distinction between those women who are victims of environment, circumstance and sexism that forces them into a submissive slave-like role whereby they spend their life in servitude to their husband resulting in an inability to gain employment or a life outside the domestic boundaries - she is NOT a lady of leisure. She is a trophy wife. Although she, and the lady of leisure, will both suffer the same lack of independence and powerlessness over their lives. Both will experience a crisis of identity. (...) As both may find themselves engaging in the prostitution of marriage - sex in exchange for a Prada handbag. These are the same individuals who turn a blind eye to a husband’s affair because they need to. Because if she walked out on him, where would the weekly allowance come from to service the new BMW? 
Up to the end of the 19th Century the lady of leisure who couldn't get independence from her husband, father, other male relative was the norm.