What is the Christological difference between the early Church fathers and the Arians?

Arius wrote to Eusebius of Nicomedia referring to the eternal Word that, '[B]efore He was begotten ... He was not, for He was not without beginning.'1 Where he qualified his argument on the fact that the Son has an eternal beginning from the Father who alone has no beginning.2 Arius seems trying to say that the Son does not exist apart from being begotten. An idea he claimed to be shared by Church fathers before him. There is a debate on whether or not precursor to Arianism can be found among the earliest church fathers before the First Ecumenical Council at Nicaea. Among the early Christian authors whom the early Church considered authoritative we can find some whose teachings are similar with the Arians that were used by the Arians to assert that their theology is patristic. What then differentiate these Ante Nicene Fathers3 from the Arians in terms of their Christology? --- 1 Arius' letter to Eusebius of Nicomedia, NPNF II:3:41. 2 '[The Son] being begotten apart from time before all things.' NPNF II,4:458. 3 Ante Nicene refer to before the Council of Nicaea in 325. They're early Church fathers who are venerated in the 24 sui juris Catholic churches, 16 canonical Eastern Orthodox churches, 6 canonical Oriental Orthodox churches, and Church of the East. Such as St. Justin Martyr, St. Theophilus of Antioch, Tertullian of Carthage, Origen of Alexandria, St. Dionysius of Alexandria, and St Lucian of Antioch.