Luke 8:10 - "And he said, Unto you it is given to know the mysteries of the kingdom of God: but to others in parables; that seeing they might not see, and hearing they might not understand."
that is exactly right! and what is the difference? the mystery is revealed to those who not only see and hear, but also do. otherwise what they think about what they see and hear means nothing, for it is made ineffectual by not doing. it is said dozens of times and in almost as many ways throughout the new testament.