INSTRUMENTAL MUSIC

	Denotes a CD composed of songs from various instrumental artists.  All sub-genres of instrumental music may be represented.
	Instrumental rock music (typically guitar based).  [Eric Johnson, Pat Metheny, Steve Morse]*
	Instrumental metal music (typically guitar based).  [Liquid Tension Experiment, Vinnie Moore, Joe Satriani, Gary Hoey, Michael Schenker, Steve Vai]*
	Jazz Fusion (typically guitar based).  [Chic Corea, Allan Holdsworth, John McLaughlin]*
	Music created with acoustic guitar.  [Ronnie Montrose, Al Di Meola, Paco De Lucia]*

PROGRESSIVE MUSIC

	Denotes a CD composed of songs from various progressive artists.  All sub-genres of progressive music may be represented.
	Progressive Rock music, as a whole, is typified by complex compositions, tempo and time signature changes, sweeping dynamics, intricate melodies, and is generally driven by guitar and/or keyboards [Rush, Deep Purple, Marillion, Pendragon, Spock's Beard]*
	Progressive Metal maintains the guitar and/or keyboard driven nature of progressive rock, but this music is characterized by powerful riffs, complex arrangements, intricate solos, and metal-style vocals.  [Dream Theater, Fates Warning, Symphony X]*
	Combining Art Rock and Adult-Oriented Rock, this music should actually fall under a Pop category with progressive tendencies. [Journey, Styx, Asia, Kansas]*
	Neo-Classical music which typically manifests itself in a harder, guitar driven interpretation of classical modes and scales. [Yngwie Malmsteen, etc.)*
	Symphonic Rock is typified by complex arrangements, significant orchestration, and multi-part suites.  Usually contains elements of classical and jazz with a strong sense of dynamics.  [Yes, Genesis, King Crimson, Pink Floyd, ELP]*
	A combination of Space Rock, Ambient, Electronic and Psychedelic, this category moves from the extremes of swirling guitars and keyboards to aggressive, seemingly un-syncopated patterns.  [Hawkwind, Ozric Tentacles, Tangerine Dream]*

* Artists have been attributed to a particular sub-genre to give an idea of that sub-genre's "feel."  Most of the music created by these artists, however, span broad ranges of instrumental and/or progressive music.

Definitions extracted from "The Progressive Rock Files" by Jerry Lucky, "Rocking the Classics" by Edward Macan and the rec.music.progressive FAQ (4/8).  Most classifications are subject to personal interpretation.