What is the specific definition of a PhD candidate?

Question

Is there a difference between a PhD candidate and a PhD student?

The reason I ask this question is because some people say once you are accepted in a PhD program you are a candidate (for a PhD). Others say you are not a full candidate until you finish your preliminaries. Please back your answer up with references.

Answer 1

Usually  a person is considered a PhD candidate after they pass their qualifying exam (at which point most have finished their coursework and just need to complete their dissertation).

Answer 2

You're a PhD student when you're in a PhD program. You're a PhD candidate when you have passed your class requirements and qualification exams.