Krishna gives Arjuna a straight answer. Both renunciation and Karma Yoga lead to moksha. Both roads reach the same destination.
But then he adds: of the two, Karma Yoga is superior. Why? Because abandoning action entirely is extremely difficult. Uprooting a large tree from its base is hard work. In the same way, pulling the mind away from all action is not easy. Letting go of attachment while continuing to act is far more practical.