The second son is somewhat more devious. He puts on a good face and immediately agrees with his father's request; however, his actions do not measure up to his words. He ignores his father's wishes and never appears in the vineyard. Jesus asks the critical question, "Which of the two did the will of his father?"
Jesus clearly has a forgiving heart and is able to see the bigger picture. It's not the first son's words that are important to Jesus, but his actions. Jesus allows room for complaining and verbal resistance. The first son, despite his original reluctance and outward show of rebellion, soon chooses obedience. He follows the will of his father and does the work to which he is called. The second son only talks a good game. He promises much and produces nothing of value.
One must walk the walk, even when it means backtracking from a poorly chosen path, and starting over down the narrow path toward eternal life.