Honestly the biggest difference between FR and Greyhawk is simply volume.
How many pages of information is there about FR compared to Greyhawk?
As far as the rest though? They’re not really all that different.
Isn't this similar to just about anything, where it depends upon how you set the "microscope" and/or one's interest level/knowledge?
For the former, I mean, both are kitchen sink fantasy settings for D&D - but that's at a macro-level. Dialing in the scope, more and more differences stand out, and differences in flavor and atmosphere emerge.
As for the latter, to me - as a non-country music fan - all country music sounds basically the same. I mean, I can pick out and enjoy Johnny Cash, but if I turn on a pop country station, it all sounds the same (and not very pleasing to my own sensibilities).
But if you ask me about the different flavors of funk music, I can give you a verbal dissertation on its variations and history. For me, there's a world of difference between, say, Funkadelic and Graham Central Station and the Headhunters.
Now if I asked a friend to browse through the
Forgotten Realms Campaign Setting and the
Living Greyhawk Gazetteer, she might say, "are these the same world?" But if she read them cover-to-cover she'd pick up differences, and if she explored the various available materials over the years, they would become even more differentiated....and even more so if she played in a campaign in both, with a DM who really "got" the respective settings.
The point being, I hear what you are saying - but only from a very macro level and/or from the perspective of a "non-connoisseur" of D&D settings, or fantasy in general. But if you dial in the scope and/or acquire a palate for fantasy and D&D settings, they stand out in greater contrast. I would say this is especially true if we take Gygax's Greyhawk (WoG box set) and Greenwood's Realms (gray box) - one
is Gygax's mind, the other
is Greenwood's mind.
As an aside, this is why I loved teaching world-building to a group of high school students some years ago. I didn't frame it as, or connect it to D&D or fantasy in any way. It was amazing how different each world was - and how each expressed the uniqueness of the student. Now if I had said, "create a world of fantasy adventure," the differences would smooth out somewhat. Many of them would have been influenced by the LotR films or Harry Potter or video games. But they'd still all have their own unique flavorings.
