We can argue about what "belief" means but I suppose simply we could say "its what you think is true".<quoted text>
Belief is what it is and only the confused will change what it means because they dont agree with the what the definition says or seems.
On that basis the issue is not what is believed but how that belief came about. For a kid it might just be that Mum said it. For a religious person it might be because a scripture said it combined with another belief, that the scripture is God's word.
For a scientist belief comes from an assertion's conformity to enpirical evidence. Even more, it wont be believed unless we know there would be observations that could falsify it if it was wrong. And it will be believed with more confidence if the idea made successful predictions about what should be observed before it was observed.
The final point is that scientific belief is always subject to doubt and there must be a willingness to change the belief if empirical evidence is found that conflicts with it.
Most scientists would say that all the above criteria make scienfific belief so different in character from traditional belief systems that the word belief no longer applies. Instead we have a degree of confidence in an assertion based on the strength of evidence and its never 100% conviction though it can get close.