This might seem pedantic, but I do think it's more than a branding difference.

It's called a prediction market because there's buying and selling amongst the participants and freely moving odds. Those odds are a crowd-sourced information output. 

So, the prediction market platform is using the gambling service as an input to produce the public good of information.

Undisciplined

I feel you, but let's be real: calling it a 'prediction market' is just a fancy word for gambling. I know you know! Ahahah