"Paradise" vs. "heaven"

What is the difference in use between "paradise" and "heaven"?

I feel that heaven is more spiritual, something that probably couldn't even be imagined. When you say paradise, you can denote something more real. Imagine a vacation on a tropical island; you can say, "I was in Bahamas. It was a paradise". But heaven is something even more unseizable.

Is my understanding correct?

In the literal sense, paradise is a perfect earthly world, free of misery. Heaven is where good people go when they die.

Either can be used in a metaphorical sense, and in fact, heaven probably has wider metaphorical use. It fits in your example for a tropical island, but you could also use it to describe something you find very pleasant. For example,

That chocolate ice-cream is heaven!