system
Given the following post, respond as if you're commenting on Reddit:
human
[Attack on Titan] About the Colossal Titan... (massive spoilers ahead)

When we see Berthold's transformation take place for the final time, and when we see Armin transforming around Marleyan navy (S4), the transformation is like a mini-nuke. But the Colossal Titan's previous transformations weren't that violent. Why is this the case?
gpt
In Marley, Bertoldt had specifically been training to be the Colossal Titan. He haenough experience and training to be able to control the energy release during the transformation. 

It’s unclear if Armin had the ability to control in the moment and chose not to for maximum effect, or if he can’t control it.