Disobedience
In the gospel sense, disobedience is not following God's commandments and is akin to rebellion, sin, and transgression.
Rebellion
Rebellion is open, willful resistance and defiance to authority, with the stress on intention, deliberateness, or purpose. It also requires knowledge of right and wrong. Rebellion may be refusal to obey, active pursuit of evil, or merely neglect, considering Christ's suffering for naught. Latter-day Saints believe that someone who engages in complete, knowing, open rebellion to God, such as Lucifer did, will, upon judgment, become a son of perdition. When people follow the example Lucifer exhibited in the pre-existence (Revelation 12:7-12), they choose him as their father and show that they prefer to be in his company. Therefore, when they die they are given their wish and are assigned to the devil's kingdom in the spirit world temporarily and then, after Judgment Day, the eternal world permanently. Those who love darkness rather than light “receive their wages of whom they list to obey” (D&C 29:45). LDS believe that a person who knowingly and willingly turns from God will have no mercy[[ and no part in the First Resurrection (Mosiah 3:11-12, 15:26). First Samuel in the Old Testament (15:23) stresses how serious rebellion against God is by saying that “rebellion is as the sin of witchcraft!”
Sin
Sinis another word for knowingly and intentionally disobeying divine law. A sin may be of commission (active)— doing something wrong or indulging in thoughts about doing it-- or of omission (passive)—not doing what is right and good. James said, “To him that knoweth to do good, and doeth it not, to him it is sin” (Jas.4:17). Just as in rebellion, sin requires knowledge of right and wrong and the deliberate choice to do wrong—or at least not to do good. Sin requires knowledge, a sound mind, and a minimal maturity (The age of accountability revealed to LDS is age eight). An LDS leader, Orson F. Whitney explained, “Sin is the transgression of divine law, as made known by a conscience or by revelation. A man sins when he violates his conscience, going contrary to light and knowledge. . . .He sins when he does the opposite of what he knows to be right.” Mormons believe a person who does not know about a commandment is not held accountable for obeying it and will face no punishment. However, they also believe that each person is born with the Spirit of Christ—a conscience against violating fundamental laws, such as murder, and will be held accountable for violating that conscience. Conscience also is pricked by simply thinking about doing wrong—a sort of self-indulgent orgy in which a person submits his mind and heart to Satan's practices. Christ points this out about adulterous thoughts, “But I say unto you, That whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart” (Matt. 5:28). This sin requires not just being tempted, which comes to all people, but allowing the wrong thoughts to continue, to yielding to those thoughts, and allowing oneself to be enticed by the devil.
Transgression
Transgression is essentially a violation of divine law, also, but in some cases may not involve intention and/or knowledge. Latter-day Saint theology differs from that of many other Christian religions in that they do not believe that Adam and Eve sinned (sin requiring knowledge of right and wrong) but only transgressed because until they ate the fruit of knowledge of good and evil, they lacked the prerequisite knowledge to sin. They were in the position of babies or very young children, who may disobey their parents but don't yet understand what they are doing. In both situations, the transgressors aren't accountable or deserve punishment, though they may still suffer consequences of their actions, such as when Adam and Eve could not remain--in their changed condition--in the Garden of Eden.