I’ve previously written that belief in something means that you only think that when you don’t know but perhaps the distinction between the two hasn’t been as well put, so here is another explanation.
Suppose I am a farmer and have a farm with many paddocks, some of which are quite a distance from the main house. One of the furtherest paddocks needs to be mowed and I ask my eldest son to mow that paddock the next day. At the end of the day we both arrive home, I from a visit in town, he from his assigned job, the mowing of the far paddock.
I have not been to the mowed paddock to actually see whether it has been mowed, but I believe it to have been mowed, and may ask my son whether he completed the task.
However if, on returning from town, I diverted from my track to the house to the paddock in question and saw that it indeed had been mowed, I would no longer need to believe my son, but now know, from personal observation, that the paddock had been mowed.
So I believe when I don’t know, and when I do know, I no longer need to believe.