Sorry, yes, there’s a terminological disconnect here: M31, say, is the “Andromeda Galaxy” to us, but the “Andromeda Nebula” to Hubble’s contemporaries circa 1920. The recognition that at least some of the cloudy (nebulous, literally) stuff in the sky is galaxies (and that the universe fits more than one) was the very point of the fight I mentioned. The world before it was thought to be drastically smaller in a way that I find difficult to think about.