Soul-Scar Mage

Oracle Text
Prowess
If a source you control would deal noncombat damage to a creature an opponent controls, put that many -1/-1 counters on that creature instead.
Card Rulings
4/18/2017 If an effect causes a creature you control to fight a creature an opponent controls, the damage is dealt simultaneously. For instance, if your 2/2 creature fights an opponent’s 4/4 creature, your creature will be dealt 4 damage and your opponent’s creature will have two -1/-1 counters put on it.
4/18/2017 If a spell or ability an opponent controls causes a source you control to deal noncombat damage to a creature an opponent controls, that damage will be replaced with -1/-1 counters.
4/18/2017 Soul-Scar Mage’s effect isn’t a prevention effect. Damage that can’t be prevented will be replaced with -1/-1 counters.
4/18/2017 If multiple prevention and/or replacement effects are trying to apply to the same damage, the controller of the creature that would be dealt damage chooses the order in which to apply them. As examples, an opponent could choose to apply the effect of Djeru’s Resolve and prevent the damage rather than put -1/-1 counters on it; or an opponent could choose to convert the damage to -1/-1 counters before Insult could double it, and then Insult’s effect won’t apply anymore.
702.79a Wither is a static ability. Damage dealt to a creature by a source with wither isn’t marked on that creature. Rather, it causes that many -1/-1 counters to be put on that creature.
I'm still not seeing the difference. Wither changes the damage to -1/-1 counters, Soul Scar Mage changes damage to -1/-1 counters. Is there something I'm missing?
This guy and cycle demon (making use of bicycle lands) can churn out an army of scarabs and insects that you can tap to crew a single aethersphere harvester so you can kill your foe with a throne.
This guy and cycle demon (making use of bicycle lands) can churn out an army of scarabs and insects that you can tap to crew a single aethersphere harvester so you can kill your foe with a throne.