Everyone knows that Hard Rock and Heavy Metal was born roughly around the same time. There are people in the world that associates them as synonyms of the same genre, while others try to get more "technical" between the two. I know many people will have many opinions on this subject matter, so I thought what the heck?
Just to lay down the facts, I remember watching Metal Evolution by Sam Dunn and his interviews with Geezer Butler of Black Sabbath and Jon Lord of Deep Purple, who we associate with heavy metal. However, during the interviews, both Butler and Lord called their bands hard rock. Geezer himself dismissed the Heavy Metal label. Even Led Zeppelin, whom people has credited aiding the developement of heavy metal, prefers hard rock and dismisses the metal label.
On the other hand, many hard rock bands such as AC/DC, KISS, Van Halen, Guns'n'Roses, and Alice Cooper have been associated one way or another with the heavy metal genre. Although AC/DC, KISS, and Van Halen have considered themselves Rock'N'Roll, their style alone is characteristic of heavy metal (e.g. AC/DC's Thunderstruck, and KISS's God of Thunder).
Many of the popular heavy metal bands (Metallica, Megadeth, Anthrax, Slayer, Avanged Sevenfold, Rage Against the Machine, Dream Theater) draws inspiration both hard rock and heavy metal.
Musically, both genres utilize many of the same techniques. Many people have even said that the line between them is blurred, which makes it easy for bands to cross between both genres-hence why some people tend to use them synonymously.
So what's your opinion on the subject? Are they generally the same, or entirely different (technicalities)?