What is dharma? Dharma is that which makes us seek for happiness in this world or the next. Dharma is established on karma, and it impels us day and night to run after and work for happiness.
What is mukti? That which teaches that even the happiness in this life is slavery, and the same is the happiness of the life to come, because neither this world nor the next is beyond the laws of nature... Again, happiness, wherever it may be, being within the laws of nature, is subject to death and will not last ad infinitum. So we must aspire to become mukta. We must go beyond the bondage of the body. Slavery will not do.
by Swami Vivekananda. Complete Works, 5:446.