Short answer
In one important sense they are lighter: the Prophet ﷺ said all of his ummah will be pardoned except those who sin openly and then expose what Allah had covered. A hidden sin is still a sin to repent from, but Allah loves to cover it, so do not announce it. At the same time, a person who keeps up a pious face but breaks Allah's limits whenever alone is warned in the hadith.
Sins done in private remain sins, but making them public, boasting about them or inviting others to them adds a further sin. A Muslim keeps his own sins covered, repents to Allah privately, and covers the faults of others. There is no requirement to confess sins to any person.
The four schools agree on this.
Explanation
The Prophet ﷺ said: "All of my ummah will be pardoned except those who sin openly." He explained that part of this is a man doing something at night, which Allah covers for him, and then in the morning saying: so-and-so, last night I did such and such. Allah had covered him and he removed Allah's cover. Posting or boasting about sins falls under this. The Quran warns those who like indecency to spread among the believers (24:19).
Allah loves to cover His servants. The Prophet ﷺ said that Allah does not cover a servant in this world except that He will cover him on the Day of Resurrection. So if you fell into a sin in private, do not tell people about it; tell Allah, and repent. Islam has no confession to a priest or imam. Only if the sin involved someone else's right do you need to deal with that person, by returning what is theirs or asking their pardon.
There is another side. A hadith in Ibn Majah, graded sahih by several scholars, warns of people who come with deeds like mountains, which Allah turns to scattered dust, because when they were alone with what Allah forbade, they violated it. The fix is taqwa in private: "Fear Allah wherever you are, and follow a bad deed with a good one, it will wipe it out."
So the rule is: hide your sins from people, never hide from Allah, and work on the habit you only do alone. See will Allah forgive me if I keep sinning?, how to repent and taqwa.
The evidence
Quran, Surah An-Noor 24:19
إِنَّ ٱلَّذِينَ يُحِبُّونَ أَن تَشِيعَ ٱلْفَٰحِشَةُ فِى ٱلَّذِينَ ءَامَنُوا۟ لَهُمْ عَذَابٌ أَلِيمٌۭ فِى ٱلدُّنْيَا وَٱلْءَاخِرَةِ ۚ وَٱللَّهُ يَعْلَمُ وَأَنتُمْ لَا تَعْلَمُونَ ﴿١٩﴾
Indeed, those who like that immorality should be spread [or publicized] among those who have believed will have a painful punishment in this world and the Hereafter. And Allah knows and you do not know.
Warns against spreading indecency.
Sahih al-Bukhari 6069
Sahih... كُلُّ أُمَّتِي مُعَافًى إِلاَّ الْمُجَاهِرِينَ ...
"All of my ummah will be pardoned except those who sin openly."
Shows that exposing one's own sin makes it worse.
Sahih Muslim 2590
Sahih... لاَ يَسْتُرُ اللَّهُ عَلَى عَبْدٍ فِي الدُّنْيَا إِلاَّ سَتَرَهُ اللَّهُ يَوْمَ الْقِيَامَةِ ...
"Allah does not cover a servant in this world except that He will cover him on the Day of Resurrection."
Shows Allah loves to cover His servants.
Sunan Ibn Majah 4245
Grading to be checked... إِذَا خَلَوْا بِمَحَارِمِ اللَّهِ انْتَهَكُوهَا ...
"When they were alone with what Allah made sacred, they violated it."
Warns those who are pious only in public.
Where the ruling is recorded
- Umdat al-Qari (Badr al-Din al-Ayni), Book of manners, chapter on a believer covering himself. The Hanafi commentary explains the hadith on those who sin openly.
- Riyad al-Salihin (al-Nawawi), Chapter on covering the faults of Muslims. Gathers the hadith on Allah covering His servants.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.