hey, so it seems like the only instruments that remain consistent throughout an entire arrangement of yours is like bass and drums. that would make sense to like explain  the fills you do to express the harmony and stuff. i mean there are outliers, the harpsichord on outside. the strings in school. but is this true, more or less?
that might be because when different instruments play the role of the bass, they are all usually called the bass. when different instruments play the role of the drums/percussion, they are always called drums/percussion. however, when many different instruments play the role of the middle/chord/melody range, people like to call those instruments by different names. so mostly i think it's a naming situation you are noticing