Two different sons

The third difference was their actions in response to adversity [or the way in which they each responded to adversity]. The younger son actively made changes by himself. He confessed that he had dishonored his father and was no longer worthy to be called his son. He was willing to become a hired servant of his father to make up for his mistakes. He realized his mistakes and corrected them / put them right. He grew stronger through adversity. In contrast with the younger son, the older son could not accept [accept perhaps not the best word - consider "agree to" or "bear / tolerate"]the celebration for his younger brother and refused to attend it. However I think he should have followed his father’s command as he had done before. Besides, he should also have forgiven his younger brother in the end because he would then have understood his father’s words, "You are always with me, and everything I have is yours.” I’d like to point out that although they took different actions, they both wanted their father’s acceptance.

Very nice summary of "The Prodigal Son" - thanks.  Very few mistakes.  Kind regards, Michael 

PS You could say "the older son could not accept the fact that his father held a celebration for his younger brother"