To my cat, both are yawning caves of doom, he's terrified of boxes of any size and description.
My cat is a rescue, and not much of his past is known, but I have a suspicion he was abused at some point.
My cats will gladly walk into carriers as long as there's no human nearby. In that scenario it's a good place for a nap. But if we need to go right now, there's no way in hell I'm getting them into carriers without a fight.
That's why I only carry my cat in a cardboard box. He's timid enough to not destroy them thankfully and putting him into them is never a problem