Complex sentence: Practitioners are often referred to as "Salafi jihadis" or "Salafi jihadists", and sometimes described as a kind of Salafi and sometimes as separate from "good Salafis" who's movement is a "precursor" to Salafist jihadism.
Split into simpler sentences: Practitioners are often referred to as "Salafi jihadis" or "Salafi jihadists". They are sometimes described as a variety of Salafi, and sometimes as separate from "good Salafis" whose movement is a "precursor" of Salafist jihadism.