fluff vs non-fluff

In this semester, i've encountered the question: what is fluff, and what is not fluff, but real substance?

I guess to me right now, 'fluff' means having the ideas, but having no sense of reality, and no idea of concretizing these plans. General comments such as 'i want to save the world' fall into this category of fluffiness.

on the other hand, to have real substance, the subject must have been thought through in a very detailed manner, seeing both sides of the argument, and justifying reasons for one side or posing your own unique, synthesis of the problem. But more than that, there is also the sense that the person knows how to approach the problem in a tangible manner, in being aware of the concrete steps that can be taken to resolve whatever issue at hand.

In other hands, having real substance is really about having the depth to have gone through a problem - and thats something that takes time, effort and energy to go through...

and i guess that the difference between fluff and non-fluff...