Looking at various metal websites and publications, the new track produced by Blind Guardian for the Sacred 2 RPG (the inevitable formalizing of the relationship between Blind Guardian and uber-nerdy genre RPGs) has been described as "progressive metal." Recently, many bands have also been labeled as progressive. Now, the ultra-rigid pedantic metalhead bastard in me wants to scream "No it isn't!"; and well, using progressive as a catch-all term in metal seems apt, since "progressive" metal seems to be on a higher level of abstraction than most other sub-genres.
People use the word "progressive" as a synonym for "complex" which others take as "superior." Blind Guardian are the genre leaders of Power Metal and show more variation than repetition in their music. They are also ahead of their time in their approaches to songwriting. Hence the rationale behind "progressive." Black Metal are the most ardent Aristotelians; they class many black metal influenced bands, which would would be best termed under the umbrella of "black metal" as not, instead using the term for an elite cadre of bands that pioneered the genre. Since the cult-like fandom of black metal enthusiasts do not own the rights to the term, it is used much more liberally than they would care for. Also of note that the label of Progressive Metal has crept up to include non-Power Metal based bands such as Opeth, Gojira and Mastodon as of late, all bands that employ death vocals in preference to clean singing exclusively.
Thus more confusion abounds when describing "Heavy Metal" and "Metal" - the latter term in favor during the late 70s and early 90s until newer audiences lopped the "Heavy" from the name and merely used "Metal" to describe the entire genre. If you ask Gen X/Y's what Baby Boomers refer to as "Heavy Metal" they may agree on Iron Maiden and such, but beyond the 90s with the rise of melodic death, nu-metal and etc., the younger generation tend to get more specific while the older generation prefer to continue to use the term "Heavy Metal" instead.
Using an abstraction ladder, I believe that we can appropriately order the terms to avoid confusion, hence:
Blind Guardian -> Power Metal -> Progressive Metal -> Metal (or Heavy Metal)
Please note that Power Metal is not a direct subset of Progressive Metal. However the genre terms have yet to please anyone beyond doubt; the bar-room debate as to whether X band is part of Y genre shall inevitably continue as we both hear the same music flowing from our speakers but ultimately decide to call it something else.