A writer’s voice is not character alone, it is not style alone; it is far more. A writer’s voice is the stroke of an artist’s brush—is the thumbprint of her whole person—her idea, wit, humor, passions, rhythms.
Patricia Lee Gauch
The most durable thing in writing is style, and style is the most valuable investment a writer can make with his time. It pays off slowly, your agent will sneer at it, your publisher will misunderstand it, and it will take people you have never heard of to convince them by slow degrees that the writer who puts his individual mark on the way he writes will always pay off.
Here's my two cents: The writer's style is in all her work, while voice is dictated by the work itself.