Is there any difference between "unproductive" and "nonproductive"?

If you can find any difference between "unproductive" and "nonproductive," could you explain that with some illustrative sentences?

Being unproductive implies that something could have been productive but no action was taken. Nonproductive implies that something was unsuccessfully trying to be productive.

John was unproductive and sat around all day watching movies.

John spent three nonproductive hours trying to write a novel.

There is a difference. Unproductive suggests something that could be useful produces nothing of value. Nonproductive suggests that same something produces nothing useful at all.

Nonproductive=achieving little

Unproductive is when something could be produced but despite the reason (ie: lack of effort, mistakes, laziness) nothing has been produced