Sometimes Jews have blonde hair and blue/grey eyes
They can mixed or Khazars,many Slavs have passed off as Jews,you know how it works.20% of Israelis come from former SU,go figure.
We talk here about the typical Jew.The Germans knew that and they used rhinometry(measurement of nose length to width ratio I think) to identify who is the Jew and who not by their nose index.They seldom failed.
"Caucasian" is just the term
In Russia with Caucasians you mean people who come from Caucasus region like Georgians,Chechnyans,Ingushetians etc.
In the US they mean the whole of white ppls.
Yes,they call them caucasian because it is more politically correct than white.And caucasian can include for example Georgians,Jews,Turks etc.
They do not make distinction between white slavic,white germanic,white mediteranean although geneticists make these distinctions.