Philosophers treat belief and knowledge as different things, even when the content is identical and the believer is correct. The distinction rests on how the belief came about.
A true belief can be true by accident
Someone who guesses the outcome of a match and happens to be right held a true belief, but almost nobody would say they knew the result.
The judgement tracks luck. What is missing is any connection between the reason for holding the belief and the fact that made it true.
This intuition is stable across cultures and ages, which is why it became the starting point for a large body of analysis rather than a curiosity.
Justification is the traditional third element
The classical account adds a requirement that the belief be justified, meaning the believer has adequate grounds for it.
Grounds can be perception, testimony, inference or memory, and each has recognised failure modes that philosophers study individually.
The account was refined for centuries because cases kept appearing where justification and truth coincided by coincidence, leaving the accidental quality intact.
Testimony carries most of what anyone knows
Very little of a person's knowledge is acquired first hand. Most arrives through teachers, texts and institutions.
That makes the reliability of the source part of the question. A belief inherited from a careful chain of transmission stands differently from one absorbed from rumour.
Religious and philosophical traditions took this seriously long before modern epistemology, developing rules for evaluating who may be trusted to report what.
Confidence is a poor guide to either
Feeling certain is a psychological state, and it does not reliably track the quality of the grounds standing behind a belief.
People are frequently confident about badly formed beliefs and hesitant about well formed ones, and the mismatch runs in both directions rather than in one predictable direction that could be corrected for.
Consequently most accounts of knowledge deliberately exclude confidence from the definition. It is treated as an effect that sometimes accompanies knowledge rather than as a mark of it, and a strong feeling is evidence about the believer instead of about the claim.
The distinction changes how disagreement is handled
If knowledge depends on grounds rather than on conviction, then a disagreement becomes a question about the grounds rather than a contest of assertions.
That reframing is practical. It gives two parties something examinable in common even where they hold incompatible conclusions, and it makes progress possible without either side conceding first.
It also explains why traditions with strong commitments still built elaborate argumentative cultures, since defending a position required saying what supports it.