The person you're replying to was saying that range of political views between Democrats and Republicans is smaller than the range of views in Europe. As you've noted, there are some Nazi-adjacent parties winning elections in Europe. There are also some communist parties that have seats in European assemblies. That seems to support the idea that the difference between Republicans and Democrats is relatively small.

Also, I don't think that even the "we want to shut down mosques" right-wing of Europe wants to eg. get rid of socialized healthcare.