I’ve got some many words for you today! They are of course all related, being all products made out of bell peppers/capsicums. The differences between EP and BP in this matter are plentiful, so I’ll present you with each separately.
[O] pimento is EP for the fruit (that is, the bellpepper itself); [o] pimentão is commonly used for its products – almost always from its red variety: for example, [a] massa de pimentão is red capsicum paste, while [o] pimentão-doce is a native name for paprika, powder made from dried and ground red bellpeppers. While [a] paprica can be used, it’s not terribly common; besides, we have a second native word for paprika, [o] colorau (check the link for [o] pimentão-doce if you haven’t already).
In EP, we also never use [a] pimenta in reference to any members of the capsicum family (including chili and other heat peppers), which is quite common in Brazil. For Portuguese speakers in Portugal, [a] pimenta is only used in reference to other spices (like members of the genus Piper, like black and white pepper; allspice, known here as [a] pimenta-da-jamaica; and Szechuan pepper, known as [a] pimenta-de-sichuan or [a] pimenta-chinesa).
In Brazil, [o] pimentão is the fruit, while [a] páprica (note the accent on the third-to-last syllable, changing the stress pattern of the word) is the term used for paprika. In Brazil, [o] colorau is also a ground, red spice like paprika, but made out of achiote (known as [o] urucu over there) seeds. I’ve never tasted this version, but I’m sure it’s just as good!