Well, my music guru friend wrote back, and here's her response (she's a little snarky - wonder where she gets that from?
)
Anyway, technically pop is not so much a musical style as a statement about it's popularity. Hence, pop being short for popular music. Really, anything that is popular is pop music but that's not really the way the word is used now so I digress. I suppose currently pop music is anything of a non-rap variety performed by white youngsters (i.e. Backstreet Boys, Justin Timberlake, Brittany, that kid from Summerland). Anything of the non-rap variety performed by black youngsters is R&B or soul (i.e. Usher, Alicia Keys, Beyonce). Then there's all manner of rap. Performed by both white youngsters (Eminem) and black youngsters (Kanye West). Gangsta rap (Ice-T, Tupac). Old school rap (Run DMC) and then the battle between East Coast rappers and West Coast rappers. Apparently, there is a difference but I haven't a clue what it is. There's the battle of the ageing rock stars (Aerosmith, Rolling Stones) comprised mostly of 50 or 60 something white men who are lucky to remember their names let alone words to 30 year old songs due to all the brain cells they've killed off from drugs. Despite their steadily decling number of brain cells these guys can still rock and therefore still deserve to be called ROCK stars. This is unlike their "pop" counterparts (Rod Stewart, Lionel Ritchie, Cher) who cannot hold their old titles and are now relegated to adult contemporary status. Back to rock music. There's often a fine line between rock and pop and is frequently decided only by the listener. Recently, there has been a fine crop of women rockers (Sheryl Crowe and Melissa Etheridge) and a few guys who aren't bad (U2, Springsteen). On to metal. Mostly characterized by long haired men with lots of tatoos and a lack of clothing on stage (have you ever seen a metal band fully clothed on stage?) Metal is a dying art these days and I can't really think of a single newish metal band unless Ed Rollins counts (I think he's metal, but he might not really be new). But never fear, there's an abundance of 80s and 90s metal (Metallica, Anthrax, Motley Crue). What's next? Punk. Big in the 70s and 80s (Blondie, Adam and the Ants). It seemed to die off a bit in the 90s but many say that grunge (Nirvana) was the new punk. I have no opinion on that matter. Perhaps punk is making a come back (Green Day) or maybe it's just that the definition of punk has been expanded (Jimmy Eat World) because some of what is now called punk is less punk and more rock. Who knows? Can't forget the singer-songwriters. The new (John Mayer) and the old (James Taylor). Often these guys are called light rock but one woman's light rock is another's adult contemporary so that's better left to you, the discerning listener. Then there's my favorite category, the formulaic rock bands, known in some quarters as crap-alt-rock (Matchbox twenty, 3 Doors Down, No Doubt and many, many more). The techno stuff (Moby) which is fine if you like slightly esoteric music. And dance music, much of which did not start out as dance music but as rock or pop and some dip of a dj sped it up and added synthesizers to form hideous mutant music (Enya's Only Time, anyone). I'm sure there are many more but I am required to do actual work from time to time so I must end Music 101 here. Hope this helped or at least provided a modicum of amusement.
Hope that helps!
:LOL
What a link! I haven't heard of half (ok, probably 3/4 :LOL ) of those genres 
