First of all, and let's get that very clear, the comparison is idiotic. For a few reasons.
1. The congressman is part of the legislative branch, while the president is the personification of the executive branch. Which is a very basic and real difference.
2. The president won't be able to order a hit on anyone willy-nilly within the United States. But hitting a military target in Pakistan or Afghanistan is something a little different. At the moment said American citizen joins a military of paramilitary force in war against the United States, he is as much a legitimate bloody target as a main battle tank or a military airport. There's far too many strikes that hit civilians for me to give even a shit about wether or not it's right to hit a military target. If we accept that wars have rights and wrongs, hitting military targets is right. In my mind.
3. The citizen recording or photographing in a public space has not broken any law, which makes any action in of itself unacceptable. Lots of Americans took up arms against the United States during WW2, Volkdeutsche I believe it was called. Were they not legitimate targets for the US GI's working their way through Europe? On the other hand, while the interning of Japanese-Americans WAS legal due to the Geneva convention, it was not legitimate due to the United States constitution. Thousands of innocent people were illegitimately detained for a long time, and that's wrong. Crucially, it happened in the United States, and against non-combattants. Even if the Geneva convention alloved it, the Supreme Court did strike down the internment ex post facto. Because it wasn't constitutional to incarcerate people regardless of any reasonable suspision.
That's the basic difference. I am sure a constitutional scholar might put forward an argument that's better, but that's my .02