確信 and 自信: conviction about a claim and presentation confidence
Compare belief in an explanation or future success with confidence developed through practice, identifying the content or ability being believed in.
Believing that something is correct or will succeed
確信 (かくしん) means conviction or certainty. In “証拠を見て彼の説明が正しいと確信した。”, seeing the evidence convinced the speaker that his explanation was correct.
“成功への確信を持って作業を続けた。” describes continuing the work with confidence in success. Continuing the work is stated; success already achieved is not.
Confidence from practice and small successes
自信 (じしん) means confidence. “何度も練習したので発表には自信があります。” connects repeated practice with confidence about the presentation.
“小さな成功を重ねて少しずつ自信がついた。” describes confidence developing gradually through a series of small successes. Keep 少しずつ rather than making one success produce complete confidence.
Distinguish the belief's target from an actual result
Compare conviction about an explanation or future success with confidence in performing a presentation. The focus is the content or ability that the person believes in.
Do not define 確信 as always objective proof or 自信 as always unsupported feeling. Even the evidence example directly states the speaker's conviction; the word itself does not guarantee that the believed content is true.
Does continuing work with 成功への確信 mean that success has already been achieved?
Show the answer and why
No. It describes continuing the work while believing in success. 自信 about a presentation likewise expresses confidence in an ability without establishing the actual performance result.