hat or cap

[rezaa]

what's the difference between hat and cap?
i have searched and found that a cap is brimless but it can be with visors, and visors are brims, aren't they? it's so confusing
how can i differentiate between:
hat vs cap
brim vs visor
thanks in advance

[Anglika]

A cap has a peak [part-brim or visor] at the front; a hat has a brim all the way round.