The difference that I meant to illustrate is that what you refer to as "Old Fantasy" invariably contains some historical fact or is based upon known historical figures. Even Sir John Mandeville's 'vegetable lamb' had some basis in fact (it is an allegorical representation of cotton). Homer's works contain notable, proven, references to actual historical places and events. And so on. The works were offered by the authors as actual accounts of real events or tales of real people, not pure fiction (regardless of what they actually were).
Contemporary fantasy fiction does not typically claim to be factual in nature, nor does is it typically marketed as being a retelling of actual, historical, events. Further, those works of contemporary fantasy that do claim such things, do not typically go to any great lengths to showcase real life geography, contemporary events, or contemporary personages within their pages. I am hard pressed to think of a Homeric poem or Germanic saga that does incorporate some (or all) of these things.
The writing techniques of the authors in question are quite different when given even the most cursory examination. The goals of the authors are also arguably very different. It is widely accepted by historians and literary scholars alike, for example, that the skalds of ancient Iceland were not writing fiction, but preserving national heritage. The same is true of the Native American oral tradition.
To dismiss all folkore and literary epics as pure fantasy with little or no value past entertainment does a great disservice, both to many countries and educated modern peoples.
