Godwin's Law specifically applies to accusations of Nazi sympathies to derail the argument, when the person making the accusation simply thinks "I don't like it, therefore: Hitler", or when the accusation otherwise has no actual basis or relevance to the discussion. Or, it's used in all honesty, but is an overall weak rebuttal. Godwin's Law applies to the following exchanges,

Person 1: Abortion should he legal because it doesn't actually kill any babies. Abortion wouldn't even be necessary in most cases if we focused on making birth control more readily available to women and emphasised contraceptives in sex education.

Person 2: But that completely ignores the fact that babies are being murdered! You're a Nazi!

And,

Person 1: Cigarettes should be more heavily regulated because of the harmful side effects they cause.

Person 2: Hitler was a nonsmoker. You are literally Hitler.

Not,

Person 1: We should deport jews and have liberal genocide.

Person 2: That's exactly what a Nazi would say.

Person 1: This is why Trump won.