It is inferred from the Holy Qur'an and traditions of the Ahlul-Bayt (a.s.) that there are different degrees of torments in hell, proportioned to the different degrees of sins on earth. The Quran considers associating partners with God (shirk) as the greatest sin. Also, God warns to punish the sinners who commit certain sins. The warnings signify the greatness of those sins.
The worldly punishments for some sins also differ from one sin to another. The punishment for some sins is flogging or capital punishment (death) and cash fine in some other cases depending on the type and intensity of the sin.
God has determined rules and injunctions for the felicity and prosperity of human beings. If a person acts upon these injunctions, he will attain the happiness of both this world and the hereafter. In case, he disobeys those injunctions, he has deprived himself of real happiness.
Sin is tantamount to disobeying God, defying Him and committing an act of transgression. The sins are different from one another in terms of their worldly effects, their consequences and punishments in the hereafter.
Classification of sins in the Quran:
The Quran considers associating partners with God (shirk) as the greatest sin. : «إِنَّ الشِّرْکَ لَظُلْمٌ عَظِیم.» [Verily, polytheism is a great injustice.] In another verse, God, the Almighty has divided sins into polytheism and less than polytheism. It says: "Surely Allah does not forgive that anything should be associated with Him, and He forgives what is besides this to whom He pleases; and whoever associates anything with Allah, he indeed strays off into a remote error." Elsewhere in the Quran, God says: "Those who avoid great sins and shameful deeds, only (falling into) small faults,- verily thy Lord is ample in forgiveness." In other words, God, the Almighty says, if you stay away from major sins, God will expiate from you the minor ones. He will forgive you for the minor sins only if you do no insist on committing and repeating them.
Classification of the sins in traditions:
The sins have been divided into major and minor ones in the sayings of the Ahlul-Bayt (a.s.). With reliance on the verses of the Holy Quran, Imam Ja'far Sadiq (a.s.) has considered the following sins to be among the major sins: Despair of Allah's mercy (Yusuf, 78), feeling secure against the plan of Allah (Al-A'araf, 99), disowning of the parents (Maryam, 32), killing of a believing person (An-Nisa, 93), accusing a chaste woman of adultery (Al-Noor, 23), unjustly eating up the property of an orphan (Al-Nisa, 10), escaping from Jihad (Al-Anfal, 16), usury (Al-Baqarah, 277), adultery (Al-Furqan, 68 - 69), betraying (treason) (Aal-e Imran, 161), not paying obligatory Zakat (Al-Tawbah, 35), magic (Al-Baqarah, 102), taking a false oath to commit a sin (Aal-e Imran, 77), breach of contract (agreement) (Al-Baqarah, 27).
The worldly punishments for some sins also differ from one sin to another depending on their degrees and types. The punishment for murder and adultery with a married woman is execution (death) and the punishment for some other sins like adultery with an unmarried woman, drinking wine etc. is flogging. For some other sins like breaking fast, covenant and oath etc. there are penalties like fasting or feeding the poor. 
When it comes to comparing between adultery and music, it is necessary to note that adultery is a much greater sin as compared to music because it has been reported from the Holy Prophet (s) that he said, "Ghina (music) is the ladder to adultery." Imam Sadiq (a.s.) says, "The house in which there is ghina will not be immune to evil and corruption." According to these two traditions, ghina serves as a prelude to adultery but we could not find any evidence to prove that the divine punishment for adultery is thirty four times greater than the punishment for haram music (ghina).
The concluding point is that although in the Islamic culture there are different degrees for sins, it should be noted that no matter how insignificant a sin may look to be it is great in the sight of Allah, the Exalted. Imam Baqir (a.s.) says, "Do not look at the minuteness of the sin, but see Whom you have sinned against."
 - The Infallibility of Prophets and Messengers by Allamah Askari, pg. 78.
 - Luqman, 13
 - An-Nesa, 116.
 - al-Najm, 32
 - النَّهِیکِیِّ عَنْ عَمَّارِ بْنِ مَرْوَانَ الْقَنْدِیِّ عَنْ عَبْدِ اللَّهِ بْنِ سِنَانٍ عَنْ أَبِی عَبْدِ اللَّهِ ع قَالَ لَا صَغِیرَةَ مَعَ الْإِصْرَارِ وَ لَا کَبِیرَةَ مَعَ الِاسْتِغْفَارِ.
 - Wasail al-Shi'ah, vol.15, pg. 319, The Major Sins of which It is Obligatory to Stay Away", hadith No.2.
 - One hundred fifty subjects from the Holy Quran, Akbar Dehqan, pg. 210 – 212.
 - Article 83 of Islamic Penal Law, title of book: Explanation of the Islamic Penal Law, Murtazavi, pg. 51
 - Tawzih al-Masail Maraje', Rules of fasting and covenant etc.
 - Questions and Answers, pg. 22, Rules regarding Music, pg.32.
 - Behar al-Anwar, vol.77, pg. 168, One hundred fifty subjects from the Ahadith of Ahlul-Bayt (a.s.), Akbar Dehqan, pg. 247.