Circuit is a very general word. Calling something "circuit relay" gives very little infomration. As you suggest naming it related to its actual function in the car would make more sense. . Why not? You'd have to ask the designer. In reality it only has to have a unique name on the car's wiring schematics for it to be identifiable, so it could be called anything. Hence no excuse to not name it sensibly.

It's basically an electromagnetic switch. I guess they have them on fuel pumps to activate the pump mechanism when you turn on the ignition and draw the fuel up from the tank. So a fuel pump relay is just a specific type for activating/deactivating the fuel pump.

It seems like circuit relay = fuel pump relay? But why does it say "circuit relay" rather than 'fuel pump relay' https://www.youtube.com/watch?v=bCrIo2Sbi78

Ok ....... a circuit relay is basically a switch... I have restored some older cars - pre circuit relays so I understand but would find it difficult to thoroughly explain . Its worth while just Googling Circuit relay.. lots of information on a more technical level.