In the Septuagint, Genesis 6:4 has sons of GOD; in Job 1:6 it has angels of GOD. The bible you are quoting from is derived from the Masoretic Text, which is a Hebrew bible that was modified with Jewish traditions.
That the translators of the Septuagint translated the words "bə-nê hā-’ĕ-lō-hîm" as sons of God in Genesis 6:4 and translated the same words as angels of God in Job 1:6 was a matter of interpretation on their part.
In the text, the words "sons / angels of God" were translated from the Hebrew words "bə-nê hā-’ĕ-lō-hîm".