A bigger/more general question that should be asked first is, "What is a 'genre'?" In the context of MC and any user's music library, it's an attribute for classifying/organizing the collection. Unfortunately, the term does not refer to any definitive classification system. One distinction that can be made (arguably) is that "rock," "jazz," "classical," etc. are
genres, while "indie," "metal," "punk," etc. are
styles. Most music can readily associated with one genre—although some belong to two, while others defy categorization. Styles are even more complicated, because most music (especially when applied to an album or artist, rather than just one track) belongs to multiple styles. The terms don't require any clear definition as they come into popular use, and they come and go over time. Since most music collections span a number of years, using styles a part of a classification system becomes very complicated.
Being rather fond of precise classification systems, I struggled with this for some time—until I concluded I would have to implement and stick to a classification system that would be arbitrary but work for me. Using the "genre" in the common sense is useful. "Rock" and "classical," for example, are so different they warrant the use of different fields and views. So it's helpful to have a genre category that's restricted to that "level" of classification.
Had I been able to determine an efficient way to capture styles from a reliable and consistent source (e.g.,
AllMusic), I think it would have been interesting to have this in list field. Had I done that, I think I would still need another field to do what my
Style field does now. That is to apply a single arbitrary style to each album. So my "styles" are just sub-categories of genre that make sense to me. And, in many cases, it only made sense to me once I got used to my own arbitrary choice. I use
AllMovies to decide in which of my categories an album best fits. And my categories are general enough (e.g., I have 11 styles of rock), I generally just assign the same style as previously used for the artist.
