God certainly DOES differentiate between NT saints and OT saints. One concerns a NATION of believers. The other concerns a BODY of believers. One has its inheritance here on earth and the Millenial Kingdom of Christ on this earth, according to the Abrahamic and Davidic Covenants God made with them. The other has its inheritance in the heavenlies. One is to be a Nation of priests and a blessing to all nations HERE ON THIS EARTH, during the Millenial Reign. The other is going to judge angels and saints. One concerns prophecy. The other concerns the mystery, hid in God from the foundation of the world. One is Israel. The other is the One New Man, the Church the BOdy of Christ.
One bread, one body, one Lord of all, one cup of blessing, we though many throughout the land, we are one body in this one Lord.
There is no difference in God’s eyes between those to whom He first revealed Himself and those to whom He revealed Himself through Jesus.