There are several approaches to genre. In his book Form in Tonal Music,
Douglass M. Green lists the madrigal, the motet, the canzona, the ricercar,
and the dance as examples of genres (from the Renaissance period). According
to Green, Beethoven's Op. 61 and Mendelssohn's Op. 64 are identical in genre -
both are violin concertos - but different in form. Mozart's Rondo for Piano, K. 511,
and the Agnus Dei from his Mass, K. 317 are quite different in genre but happen
to be similar in form. Some treat the terms genre and style as the same,
and state that genre should be defined as pieces
of music that share a certain style or basic musical language.
Others state that genre and style are two separate terms, and that secondary
characteristics such as subject matter can also differentiate between genres.
A music genre could be defined by the techniques,
the styles, the context and the themes (content, spirit).
Also, geographical origin is sometimes used to define the music genre, though
a single geographical category will normally include a wide variety of sub-genres.