Based on the comments on a question on another SE site, I'm trying to define the difference between something being "Dependent upon something" and being "reliant upon something".
The sentence in question was: "It is well know that if you feed animals that they become dependent." The comments devolved into a debate over whether the animals were dependent on the provided food, or whether they were reliant on it.
One contention was that the former is a subset of the latter - if you rely on something you can find other sources, but if you depend on it, you can't. The other was that they were entirely equivalent, which the dictionary seems to support.
Is there a correct usage? Are there implied differences that a straight dictionary lookup doesn't provide?
Edit: Answers based on the verb forms (depends and relies) would be fine, if they transfer over to these adjectives, but not ones based on the positive adjective form (dependable and reliable).