Is logical fallacy different from logically false?
I believe that by definition yes, but perceive that every day language often suggests that logical fallacy means logically false. That's, if something contains fallacious reasoning, then it's also false.
By def. logical fallacy means "loose reasoning", which doesn't follow "truth evaluation" properly. That is, it might do derivations, which are not "valid", between logical steps.
Then the use of logical fallacies in this contexts also skews the view on their meaning. Because then Ad Hominem could be used to make argument false, even when as just a fallacy, it merely suggests that the reasoning might have "deviated" from the context that it should have stayed in. That is, that "you're ugly and fat, therefore your argument is false" is fallacious.
However, if one postulates that "arguments of ugly and fat are false", then certainly it's a true statement by definition. And there's no particular reason, that I can see, why such premise could not be taken. Since it's about as "valid" as "arguments of ugly and fat are true" or "arguments of ugly and fat behave like all other arguments".