The plot is greatly changed in the film. In the musical, Claude is a member of a hippie "Tribe" sharing a New York apartment, leading a bohemian lifestyle, enjoying "free love" and rebelling against his parents and the draft; but he eventually goes to Vietnam. In the film, Claude is rewritten as an innocent draftee from Oklahoma, newly arrived in New York to join the military. In New York, he gets caught up with the group of hippies while awaiting being sent to Army training camp. They introduce him to their psychedelically inspired style of living, and eventually drive to Nevada to visit him at a training camp. In the musical, Sheila is also an outspoken feminist leader of the Tribe who loves Berger and also Claude. In the film, she is a high-society debutante who catches Claude's eye. In the film, Berger is not only at the heart of the hippie Tribe but is assigned some of Claude's conflict involving whether or not to obey the draft. A major plot change in the film involves a mistake that leads Berger to go to Vietnam in Claude's place, where he is killed. The musical focuses on the U.S. peace movement, as well as the love relationships among the Tribe members, while the film focuses on the carefree antics of the hippies.[2]
The film omits the songs "The Bed", "Dead End", "Oh Great God of Power", "I Believe in Love", "Going Down", "Air", "My Conviction", "Abie Baby", "Frank Mills", and "What a Piece of Work is Man" from the musical. The latter five songs were originally recorded for the film, but were eventually cut, as they slowed the pace of the film. They can be found on the motion picture soundtrack album, although they were omitted on the 1990 reissue. A few verses from the songs "Manchester, England" and a small portion of "Walking in Space" have been removed. While the songs "Don't Put It Down" and "Somebody to Love" are not sung by characters in the film, they are both used as background or instrumental music for scenes at the army base. A new song written by MacDermot for the film is "Somebody to Love". There are several other differences from songs in the movie and as they appear on the soundtrack, mainly in omitted verses and different orchestrations. One notable difference is that the Broadway version used only a jazz combo while the movie soundtrack boasts orchestrations that make ample use of full horn and string sections.[3] Many of the songs have been shortened, sped up, rearranged, or assigned to different characters to allow for the differences in plot.