|The Buddha in the tree at a temple in Thailand|
(photo from the blog "Life as you make it...")
The issue is using words to speak about Zen. Words are imprecise, which is why Zen is usually transmitted wordlessly. The statements are contradictory if we focus specifically on the words and what they mean, but if we read between the lines at the understanding that these words are trying to convey, we can conclude that both statements are true and are in agreement.
We find Buddha nature through our mind, and it is the only place we can find it. However, we cannot say the mind is Buddha in a concrete way because the mind is an object just like a book or a couch or a TV set. Living things have Buddha nature, but that does not mean a cat or a whale or myself are the Buddha.
Wine has flavor, but it is not flavor. A balloon is filled with air, but it is not air. The mind is the Buddha, but the mind is not the Buddha. No object, concrete or abstract, is the Buddha. But all living things are the Buddha.
I think this is the best I can do to explain.