What's the difference between Lassitude and Slothfulness?

Quotations

* 1874 , (Marcus Clarke), (For the Term of His Natural Life) Chapter VII *: Rufus Dawes, though his eyelids would scarcely keep open, and a terrible lassitude almost paralysed his limbs, eagerly drank in the whispered sentence. * 1919 , *: "Then it's No, darling?" he said at last. *: She gave a gesture of lassitude . She was exhausted. *: "The studio is yours. Everything belongs to you. If you want to bring him here, how can I prevent you?" * 2004 , "Is Slacking the Only Way to Survive the Office?," The Scotsman (Edinburgh), 16 Aug, *: In order to appear busy, one should pace around the office clutching files.... The best part of this ancient ritual is that it tends to make one's colleagues look away—just in case you and your papers are going to interrupt their own lassitude . * 2004 , Rob Hughes, "Soccer: The Olympic Flame Running Low on Fuel," International Herald Tribune (Paris), 11 Aug., *: At Euro 2004 and the 2002 World Cup, Blatter commented this week, many stars were physically and mentally exhausted, and left an aftertaste of nonchalance and lassitude .''