Creature card v creature

[Destore117]

So for effects like {Colfenor's Urn} does it include discarding/milling creature cards into graveyards? Or only creatures from the battlefield dying going to the graveyard.

Are creature "cards" considered "creatures"

[Remillo]

Creatures only exist on the battlefield, Creature Cards exist everywhere.  Also, if you actually read the card it says "Put into your graveyard from the battlefield."  But anyways, the reason Colfenor's Urn is worded the way it is so that if someone steals your Treefolk and it dies, you can still exile it under your Urn, since it's going to your graveyard.  If it simply said "you control dies..." that wouldn't be the case.