What's the actual difference between greater vs metro cities?

https://lemmy.world/post/15411189

What's the actual difference between greater vs metro cities? - Lemmy.World

I hear some cities call the larger area as metro (Vancouver) and other cities call it greater (Toronto). Is there a functional difference? Generally speaking, is one more urbanized than the other?

I feel like metro has more of a concrete definition and greater is more colloquial. I also feel like greater might sometimes include some further flung nearby communities.