Thanks for asking. I actually do see a difference between gothic metal and gothic/goth rock. But to me, any music labelled as "gothic" should have a gothic feel to it - a dark, brooding, but still romantic quality. Tristania's "Widows Weeds" is a great axample of an album I'd consider gothic metal. Paradise Lost's albums (through "Icon" at least) and Theatre of Tragedy's releases (until "Musique" or whatever that was) are also good examples. From an atmospheric standpoint, I'd even consider Opeth's albums to be gothic in nature.
And I just don't hear that same gothic quality from bands like After Forever, Within Temptation (playing on my stereo right now, incidentally), or Nightwish. They are all good bands, they just don't sound particularly gothic.
I get defensive about it because I've met some people in the metal community who write those style of bands off as "that crap that goths listen to." Me and you know that gothic metal and the goth "scene" are two different animals, but not all do. I get annoyed at seeing those bands dissed, but I also get annoyed at people's flat-out ignorance about a subculture they know nothing about. But for the most part, my belaboring is meant to be half-comical anyway. I mean, a lot of us have our personal gimmicks