Jesus was born among both the physical and spiritual seed of Abraham. The unfaithul and faithful.
Therefore the difference between the physical and spiritual seed of Abraham is faithful service.
If you grasp this simple truth, you will understand who the chosen are, known as the true Israel of God, the Body of Christ, the church of the living God.
Hebrews 2:12 KJV Saying, I will declare thy name unto my brethren, in the midst of the church will I sing praise unto thee.
Psalms 105:6 KJV O ye seed of Abraham his servant, ye children of Jacob his chosen.
Otherwise, you will confuse the spiritual and physical seed as one and the same, which many sadly have to include the Jews that Jesus rebuked.
John 8:37 KJV I know that ye are Abraham's seed; but ye seek to kill me, because my word hath no place in you.
John 8:43 KJV Why do ye not understand my speech? even because ye cannot hear my word.
John 8:44 KJV Ye are of your father the devil, and the lusts of your father ye will do. He was a murderer from the beginning, and abode not in the truth, because there is no truth in him. When he speaketh a lie, he speaketh of his own: for he is a liar, and the father of it.