Is there a difference between an adaptation and heavily inspired?

So, there are a number of books that are very similar to older works. Some writers also adapt well-known stories. Some of my stories are adaptations, others are heavily inspired. For example, Street Thieves And Artful Dodgers, which I'm drafting in bits and pieces, is heavily inspired by Oliver Twist, with more than a few changes beyond its setting in a futuristic version of the Five Points slum in Manhattan. ( Oliver is forced to con Mr. Brownlow by Fagin's rival, the gang leader Monks. ) So, is there a line when "heavily inspired" becomes an "adaptation"? Where is the line drawn? Is there even a difference?

edited 16th Aug '13 5:26:37 AM by MorwenEdhelwen

I'd say that an adaptation is when you set out, from the beginning, to make a work based on another existing work, even if it ends up very different from the source material. Meanwhile, "heavily inspired" is when you DO want to create your own original story, but you take ideas and inspiration from existing work(s) because you like them.

And, of course, it's an easy way to get around legal problems. It's not an unauthorized adaptation, it's just "heavily inspired"!

Would it still be an adaptation if the person gave up on adapting?