For one thing, "fascist" is used here in a way that has nothing to do with actual fascism, but is shorthand for "people we don't like".

Islamism is a term with many definitions, but broadly speaking, it is a political movement that advocates the integration of Islamic theology and law with the political sphere. More importantly, it is no more necessarily violent or terroristic than, say, Christian Dominionism is (that being the closest analog I could think of).