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Album rock (often associated with the album‑oriented rock, or AOR, FM radio format) refers to rock music created and programmed with the album as the primary artistic unit rather than individual hit singles. Emerging on U.S. FM radio in the early 1970s, it spotlighted deeper album cuts, long-form tracks, and cohesive sequencing, drawing heavily from progressive, psychedelic, art, hard, blues, and folk rock. Musically, album rock favors full-band arrangements, extended solos, dynamic contrasts, and high-fidelity production intended for immersive, start-to-finish listening. While overlapping with “arena rock” and later “classic rock,” album rock is best understood as an album-centered approach and a radio culture that shaped how rock acts wrote, produced, and presented their music.

Heavy metal is a loud, guitar-driven style of rock defined by heavily distorted riffs, thunderous drums, and powerful vocals. Its musical language emphasizes minor modes, modal (Aeolian, Phrygian) riffing, and energy over groove, often featuring virtuosic guitar solos and dramatic dynamic contrasts. Emerging from late-1960s blues rock and psychedelic experimentation, heavy metal codified a darker, heavier sound with bands like Black Sabbath, Deep Purple, and Led Zeppelin. The genre values weight, intensity, and grandeur—whether through plodding, doom-laden tempos or galloping, high-energy rhythms—paired with themes that range from personal struggle and social critique to fantasy, mythology, and the occult.

Metal (often used to mean heavy metal in its broad, umbrella sense) is a loud, guitar-driven style of rock defined by high-gain distortion, emphatic and often martial rhythms, and a dense, powerful low end. It foregrounds riff-based songwriting, dramatic dynamics, virtuosic guitar solos, and commanding vocals that range from melodic wails to aggressive snarls and growls. Harmonically, metal favors minor modes, modal color (Aeolian, Phrygian), chromaticism, and tritone-inflected tension, while thematically it explores power, mythology, the occult, social critique, fantasy, and existential subjects. While adjacent to hard rock, metal typically pushes amplification, distortion, precision, and thematic intensity further, forming a foundation for many specialized subgenres.