It’s not at all a silly question. Pimento’s became en vogue back in the 50’s and 60’s and were a canned commodity that was exotic. Over time they became incorporated in a lot of types of cooking but have been originally been meant for Spanish Paella. The term Pimento is ambiguous but it refers mainly to a type of red heart shaped pepper when fully ripe. The Jalapeno similarly is called two different things when ripe and unripe. For a long time America used only green bell peppers, so the same thing red seemed exotic. I don’t think i’ve ever seen the term used on anything but canned red peppers. I am not sure why this term is still used, as it’s archaic and no one really knows what the hell is means. It’s literally a sense of something being the same and having different labels. When I go to the store I see jarred red pepper and jarred pimento’s and it’s literally the same thing. Pimento is the term you see as the same root used in Pimenton, for Paprika, and it all comes from the same species of peppers. The one takeaway you could utilize is that they are less spicy (hot) as many peppers from South America. If you have ever Drank a Martini with the Olives, as I like to do, the red bit in the middle that is not at all hot but is very mild is the Pimento.