Is there a difference between knowledge and belief
Knowledge is based, either directly or through a proxy, upon known facts that are some combination of repeatable, consensually experiential, and testable. Sound travels at a particular speed in our atmosphere. This is knowledge.
Beliefs are based upon faith, and cannot be proven, although they can be described and so passed along. Animals cross the rainbow bridge when they die. This is belief.
Either one can be mischaracterized as the other, but examining the issue at hand for the required elements of knowledge will very quickly determine just what it is you're dealing with. Likewise, conviction isn't the issue.
The thing to remember is that just because you have an idea in your head, that doesn't qualify it as knowledge.