If a brother paid half the price of a plot of land registered in his father's name, can he claim his share 14 years after his father's death, despite his previous statement "there is no difference between us"?

The money your brother paid for the land could be one of two things:

First: It could be a donation to your father. In this case, the land belongs to all his heirs after his death, and your brother cannot retract his donation, according to the hadith: "The one who retracts his gift is like a dog that vomits and then returns to its vomit." It is not permissible to retract a gift after it has been received, except for a parent regarding what he gives his child, or a gift intended for compensation that has not been received.

Second: He might have paid the money with the intention of partnership and ownership. In this case, he owns half of the land, and his delay in claiming it does not harm him.

You must ask your brother about his intention when he paid the money and said, "There is no difference between us." If he did not intend it as a donation, then he has the right to claim his share. The determining factor is the intention at the time of payment, not afterward.