Well, there's a couple things here. One is the linguistic side of it. Führer means leader, and is rarely ever used in Germany today since WWII in place of other words. If it's used, it carries negative stigma because of it's association to Hitler. Today politicians are called whatever their position is (i.e. chancellor) rather than Führer, and the word Führer was really only used in the case of Hitler and hasn't been used since to describe someone's position. It was really a term to glorify Hitler rather than describe his political position, since he was technically chancellor of the Weimar Republic even until 1945 since he gained his power legally.

Which brings me to the second point, which is the political side of it. The enabling acts following the Reichstag fire were passed by the German parliament granted the chancellor, Hitler, essentially unlimited power without the need to respond to or check with the Reichstag, essentially making him the de facto dictator of the German state. So, that differs from the president of the US since the president isn't a leader that can essentially do what s/he wants: they need to act according to the law and under the limitations of the law, specifically by checks and balances. While Hitler ultimately gained dictatorial power legally, it was through weaknesses of the Weimar constitution. The US constitution doesn't have the same weaknesses that the Weimar constitution did, thus a US president would never be able to gain the same unlimited power Hitler did legally; rather we have checks and balances that prevent a US president from acting as a dictator and in line with the constitution.

Edit: grammar and words.