According to Wikipedia, there were about 500,000 American Jews serving in the US forces during World War II, and another 500,000 Jews served other Allied nations.
Some of these servicemen would have been captured by the Germans. What treatment would they have received? Would the Germans have treated Jewish POWs differently?
Note - this is similar to, but not the same as, How did the Nazis justify the differences in the way they treated Jews v. POWs?
British and American POW's were treated as POW's. Soviet Jewish POW's were usually treated as Jews, if their national origin could be determined. The justification was that Soviet Union did not sign the international convention about POW's. Of course, this was the official point of view, but actual treatment depended on commanders in the field.
Official point of view was reflected in the so-called Commissar's Order issued before the invasion of Soviet Union. This order prescribed to select Commissars, Communists and Jews from POW's and shoot them on the spot. But not all commanders obeyed this order. Some high standing German commanders refused to pass this order to the troops. As a result, Jewish POWS were treated variously on Soviet theater.
Soviet citizens, except peasants carried the so-called "internal passport", where everyone was assigned a "nationality", which could Russian, Ukrainian, Jew etc. Military personnel did not carry this passport. So to determine that someone "is a Jew" was possible only from the words of other POW's, or checking for circumcision.
Corrections and references. The Commissar order is cited in this Wikiedia article: https://en.wikipedia.org/wiki/Commissar_Order I do not know whether this citation is complete but it does not explicitly mentioned Jews. In some documents they were disguised under the name "politically undesirable", like in this original document: http://avalon.law.yale.edu/imt/1519-ps.asp which mentions "politically undesirable nationalities and racial groups". What happened in reality is described in this Wikipedia article: https://en.wikipedia.org/wiki/German_mistreatment_of_Soviet_prisoners_of_war
EDIT. There are many books which address the question, for example, Alexander Dallin, German rule in Russia, 1941-1945: A study of occupation policies.
In general, the treatment of Jewish POWs was at the "low end" of what it was for others of their "nationality."
POWs who were Soviet Jews were treated very badly--because they were Soviets. Things were a bit worse for men who were both Soviets and Jews, but it was basically "Soviet" that determined their treatment.
POWs who were American or British were often segregated from non Jewish compatriots. They were then given unpleasant tasks that others of their nationality were spared, but still not treated as badly as Soviets or other "easterners," Jewish or not. In the back of their minds, the Germans thought of them as e.g. "Americans."
Put another way, the Nazis considered their POWs "Americans" (or "Soviets") first, Jews second.
The Jewish POWs of Western nations were separated from other POWs, moved to a separate camp at Berga and assigned more hard work. In about 2 months in one camp where the Jews were assigned mining works, 20% of them perished. This is compared to 2% of death rate among non-Jewish POWs. Fortunately to the imprisoned Jews, the war soon came to the end, so only about of 1/5 of them died. If the war continued, they all would eventually die.
Formally Germans claimed that they treated Jewish POWs according the Geneva convention but in reality the conditions differed a lot. On the other hand, on the Eastern front about 60% of all POWs died in camps.
