In fact, let me explain that former point:
- A remix is the vocals of a song with new background instrumentation.
- A parody is a song with the lyrics changed, usually with humorous intent. These are often heard among elementary school kids; "Deck the Halls With Gasoline" and "Glory, Glory, Hallelujah, Teacher Hit Me With a Ruler" are examples of this, but so is much of Weird Al's work. Parodies can also exist in other mediums, as well; Spaceballs and The Hitchhiker's Guide to the Galaxy are non-musical parodies.
- A cover is a new version of a song from another artist or band. Sometimes, the songs end up sounding very different; take a look at Alien Ant Farm's version of "Smooth Criminal" versus the Michael Jackson original. Contestants on shows such as American Idol, The X Factor, The Sing-Off, and The Voice do covers quite frequently.
Of course, sometimes they do end up butchering it; just yesterday, my ears were assaulted by the "Billboard Remix" (?) of "Leave it All to Me," the theme from iCarly, on the iSoundtrack II CD I recently got from the library. That's not the only one; on the Veggie Rocks! album, Rebecca St. James ruined the VeggieTales theme song by turning it into a rock anthem. As for parodies, while searching online for "Randolph the Red-Nosed Cowboy" a few years ago, I found an obscene "spoof" (notice the quotes?) of "Rudolph the Red-Nosed Reindeer" that was obviously written by some sick-minded individual.
It's no question that entertainment today has become very derivative, but, then again, it always has been. Though basing movies on video games, theme park rides, board games, and instructional manuals may be relatively new, many classic films--The Wizard of Oz, Star Wars, 101 Dalmatians, and countless others--were based on or inspired by literary works and/or previous films. It's as King Solomon said in Ecclesiastes 1:9 (NIV 1984): "What has been will be again, what has been done will be done again; there is nothing new under the sun." Maybe I'm just a nerd, but I like seeing reinterpretations of established works; after all, that's most of what's coming down the entertainment pipelines these days.