Why Dorian turned out to be murderous while Henry was just mischievous?

Dorian is completely immersed in pleasure seeking but doesn't want it advertised.... he isn't willing to have his name blackened by his most questionable actions. When Basil begins to question Dorian, he becomes nervous..... even threatened, though his best friend is not in anyway acting threatening. In order to avoid his questions and keep his secrets, Dorian kills him. He is desperate, and his murderous intent is a direct result of his desperation.