I think that it is a bit on the challenging side to actually find points of difference between both settings. One point of contrast would have to be that the presence of "the other" in one realm is more real than the other. Communists and the presence of Communist infiltration in American government and society was a real threat. The fear of witches was more rooted in superstition and hyperbolic senses of personal fear. The battle between Communism and democratic leadership in the West was a real and defining element. The war between both sets of ideology was a real entity, and much more valid than the fear of witches. In no way does this excuse McCarthy's hearings and conduct, but he gained traction from a political and social point of view because of the basic element that Communism was real and, at the time, presented much about which Americans possessed fear. Miller does not see the difference between both for sake of the drama and the ethical themes he sees in both. However, I think that one specific point of difference between the settings of Salem and the House Unamerican Activities Committee's driving motivation was that the latter was much more real and identifiable than the former.