Evaluate the ending of “Ode to a Nightingale.” What is the difference between a vision and a dream? What are the implications for the ambiguity?

When the Nightingale flies away, the man feels an intense loss. His dream of becoming part of the gentle bird's world are dashed. His vision of the nightingale is a momentary peek into a hidden world that must stay hidden for him. Entering this world is merely a dream. The animal world has a spirituality to it that man seemingly can not enter. The speaker sees it as a sort of primordial dream when he once might have been a part of it.

explain the ending two lines of ode to a nightingale