The difference between A and B amounts to that A is beneficial while B is not.
I don't know if "that" is properly used in this sentence. I couldn't come up with a better sentence which is as concise as this. I appreciate your suggestion.
If you really need amounts to in there:
The difference between A and B amounts to A being beneficial while B is not.
The usage of that in "amounts to that" is different.
You might not think you were hurting her, but everything you did amounts to that.