"Sin" in the singular denotes a sinful lifestyle.
"Sins" in the plural denotes a list of sins. So they don't mean the same thing.
The latter may be nothing more than a form of reformation. Or, even if it is sincere, it is not necessary and may do more harm than good. It is not essential in God's plan of salvation.
Consider the following scenario:
An evangelist comes to town to preach in the local Baptist Church. He is well known and a good number of unsaved are also in attendance. At the end of a particular powerful message he gives an invitation but in his message he had emphasized that you need to repent of all your sins. If you don't repent of all your sins you can't be saved. Some come forward--too many for the pastor to counsel with. He enlists the help of some other of his members.
One "sinner" does want to be saved. The preacher had said that he needed to repent of his sins, so in his prayer he begins to tell God how sorry he was to commit adultery with so and so, to sell those drugs to those children, to take advantage of that particular girl, to steal from the local hardware store, etc. etc. And the counselor is there with his eyes closed and his jaw dropped. "Repent of all your sins." What he has just done may be of irreparable harm, given fodder for gossip, harmed not just himself but the reputation of others.
Repenting of individual sins does not mean confessing them before others. Neither does it mean listing them. But to many it does, and can have that meaning. It may not to you, but you don't know that it will to others.
Repentance simply means a change of mind. Look it up in any lexicon. It does not mean a turning from sin. It means to turn, to change, as in to change direction, to turn around. One must turn from the direction they were going (the way of sin and the world; the way of rebellion) and turn toward God, and submit to him. That is what repentance is. It is from...toward.... It is a change in direction. There must be "repentance toward God," and that does not come without faith. Faith and biblical repentance accompany one another. They are a package deal. You can't have one without the other. They are two sides of the same coin.
That speaks of fruit--after the fact.
God commands the sinner to repent of trying to get saved by own efforts, for Jesus did that for them, but if it really means to repent of all sinning before coming to Jesus, none of us here would be saved!