Cutie Demarking

[ggg-2 3,555]

In Cutie Markless/The Cutie Map, when the ponies are stripped of their cutie marks, their colors become desaturated and more grayscale, similar to being Discorded. However, in Twilight's Kingdom, Ponies lose their cutie marks when their magic is stolen, but their colors remain the same, save for their eyes clouding over. Why? 

[Ashen Pathfinder 16,164]

I'd say it's just two different spells having similar, but not the same, effects. Tirek completely removed the cutie mark; leaving a blank flank. Starlight Glimmer, on the other hand, removed the cutie mark but replaced it with the equals sign. As we can see, the magic involved is completely different.

 

In regards to Tirek, and if we take his FIENDship comic as canon, his power completely zaps a ponies talent and cutie mark; making it disappear. We see him learning this spell from another centaur in his homeland in the comic.

 

As for Starlight, she just removed the cutie and kept it locked away.

[MLPFanatic34 3,241]

I do wonder if eventually the mane 6 would have turned into the towns ponies having shorter manes and tails? It is interesting that the spell Starlight did caused ponies to become grey and dull and almost zombie like.

[Adorkable 2,737]

Yeah, I think Pathfinder nailed it. It's all completely different types of magic.