One man is trying to do the least he can, and by his actions he forfeits the opportunity to act in the Messianic role as a Redeemer. Boaz however is different, and accomplishes redemption. Through this Ruth is assured of a future and receives a new identity, as the wife of Boaz and a mother in Israel. An outsider to the covenant of grace has been brought in.
Read Ruth 4:1-22