Although there are many similarities surrounding both groups, Tool and A Perfect Circle also share many conclusive variations. Maynard James Keenan heads both bands with his distinct vocal style. One may suspect that the style and sound of both bands would be very similar considering they share the same vocalist. However, Maynard's versatility allows him to completely change his style at random, right along with his mood. Tool has been performing since the early 1990s. A Perfect Circle began performing in 2000. Tool displays a dark, humorous image with their styles of music. With A Perfect Circle, Maynard experiments with his sensitive side influencing their music with a bright, less rigid contribution on vocals. .
In comparison, the lyrics of both bands, influenced by Maynard's background and spirituality, tend to include plenty of religious content. Tool's music seems to be completely driven by spiritual energy while A Perfect Circle has a broad range of power behind it's song-to-song change of subject matter. .
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Two songs that deliver similar feelings are Tool's song "Eulogy" and A Perfect Circle's song "Judith". Both songs include religious content that seem to speak directly to someone who has experienced personal spiritual confusion. One can begin to identify Maynard's background by comparing these two tracks. One may sense anger and distrust toward organized religion coming through the symbolism of the serious and sometimes sarcastic material. .
In contrast, the overall mood of the music between Tool and A Perfect Circle is completely different. One may find themselves expressing their own anger and resentment while listening to some of Tool's music. However, A Perfect Circle plays melodies that one could imagine an angel would play. .