What are the differences between applying for a Non-O marriage visa and a Non-O visa for raising a Thai child?

Basically the same thing and most offices won't even let you use "raising half thai child" as the reason for your extension IF you're married to the thai mother, they make you do "marriage to a thai"

The people who are on raising thai child extensions as a rule are foreign fathers who were not married to the thai mother when the child was born, and who've gotten legal parental rights granted via the Amphur or thru family court to use the child as a reason to stay.

The only REAL difference in the two visa/extensions is that there is no officially listed 'seasoning' for the 400k baht when getting a raising half thai child extension, versus the 2 month seasoning for married to a thai extension BUT more and more offices are making people on those raising children extensions season the funds anyway..

In short there's really no upside, it's virtually the same paperwork, you still get a 30 day under consideration stamp, you still get the home visit (if your office does those) and

you still take the child / your thai wife to the extension process even if you're getting the extension only based on raising a child.