In Perek Aleph Halakha Aleph: כיצד מתוודין אומר אנא השם חטאתי עויתי פשעתי לפניך ועשיתי כך וכך והרי נחמתי ובושתי במעשי ולעולם איני חוזר לדבר זה. זהו גופו של וידוי.
Basically, Vidui articulates the various elements of Teshuva. Teshuva itself is something which happens internally and Vidui articulates, which is why, for the most part, the Nusach havidui mirrors the various elements of Teshuva. So when the Rambam in Perek Bet Halakha Bet says: Umah hi hateshuva? הוא שיעזוב החוטא חטאו ויסירו ממחשבתו ויגמור בלבו שלא יעשהו עוד שנאמר יעזוב רשע דרכו ואיש און מחשבותיו וכן יתנחם על שעבר ויעיד עליו יודע תעלומות שלא ישוב לזה החטא לעולם.
So you have the ויגמור בלבו שלא יעשהו עוד—ולעולם איני חוזר לדבר זה. You have the Yitnachem al she'avar—you have the Nichamti. The Ya'azov hachote cheto clearly is the acknowledgment that there has been Chet—Asiti kach vekach. But what the Rambam has in the Nusach havidui that he doesn't include in his description and definition of Teshuva is the Busha. The Rambam doesn't write in Perek Bet Halakha Bet that part of doing Teshuva is Yitbayesh, and yet it is included in the Nusach havidui. So perhaps the Pshat is as follows. משל למה הדבר דומה. Let's say you have a teenager who recently obtained his driver's license. So he asks, he wants the car at night. So his parents tell him that he can have the car at night, but on the following conditions: he can only have one other person in the car with him and he can't be playing any music. He has to be able to be focused on the driving. So what does he do? So he piles seven people into the car with him and the music is blasting. And then he goes and he gets into an accident and he totals the car. So he's right away filled with tremendous remorse at not having followed his parents' directives, at not having honored his commitment. He certainly realizes what a terrible mistake it was and he's determined never to repeat the mistake. He's not embarrassed yet. He experiences the Busha when he has to go home and tell his parents what happened. When he goes home and he has to look his parents in the eye and tell them what happened, so then he feels the Busha. Kol zman that he doesn't come face to face with the parents, so he'll have the regret, he'll have the remorse, he'll have the determination never to do it again, he'll certainly have the Hakaras hachet of what he did wrong and what went wrong, but the Busha is when he comes face to face and has to acknowledge the betrayal. That's when the Busha will happen. So the Rambam writes here that כל מצוות שבתורה כשיעשה תשובה וישוב מחטאו חייב להתוודות לפני האל ברוך הוא.
Obviously, on one level, everything is Lifnei hakel. לא יהיה לך אלוהים אחרים על פני. Everything is in Hakadosh Baruch Hu's presence. But there are some mitzvos where it's defined not just that we're in Hakadosh Baruch Hu's presence, but that we're addressing Hakadosh Baruch Hu. When a person is going through life and he's in the office and he's carrying out his job, he's not addressing Hakadosh Baruch Hu. He's in the presence of Hakadosh Baruch Hu, he's not Lifnei hakel in the sense that the mitzvah is that he's having an audience with Hakadosh Baruch Hu. He's having a Yechidus with the Ribono Shel Olam. He's addressing the Ribono Shel Olam. Now, that's reserved for something like Tefilla, but that's also the Rambam's definition of Vidui. Vechayav lehisvados is Lifnei hakel. So the Vidui is the analog in terms of, is the Nimshal to when the child has to go home and he has to look his parents in the eye and tell them what happened. So that's what triggers the Busha. The Busha happens at the stage of the Lifnei hakel. Kol, the Teshuva is again in Hakadosh Baruch Hu's presence, but it's not addressing. Hakadosh Baruch Hu. But the viduy is lifnei hakel, addressing Hakadosh Baruch Hu. That's what triggers the busha. It's very meduyak in the pesukim also. The pasuk says acharei shuvi nichamti. Nothing to do with, the navi in Yirmiyahu is not addressing Hakadosh Baruch Hu, acharei shuvi nichamti. But then the end of the pasuk of בושתי וגם נכלמתי להרים פני אליך, the busha is expressed when the chotei is addressing Hakadosh Baruch Hu. So mimaila that's what the Rambam includes the boshti in the nusach haviduy, but he doesn't include it in his description of mah hi hateshuva.