Theme is the broad and lasting idea or impression that an artistic work leaves on its audience. Both Burgess' novel and Kubrick films address similiar ideas of totalitarianism and individuality in an oppressive society. Both works address these themes, but it can be said that one or the other does so more effectively.

Free Will

As it is in the novel, it is the priest that calls into question the morality of the Ludo Vico treatment. This moral question of how much society is willing to suppress it's free will for the sake of security and conformity pervades both works.

Violence

In this scene Kubrick introduces us to the idea of ultra violence. Unlike in the novel, Kubrick presents such violence in an almost comical tone. This contradicts with the more serious and purposed violence estabished more concretely in the novel.

Art as freedom or propoganda

Here the audience is able to experience a power that cinema has that writing cannot use. By being able to actually hear Beethoven's 9th in the film, the audience is able to more concretely identify with Alex's struggle. The physical experience of hearing something that Alex used to empower him turning him powerless shows the amount of control that an overbearing society can have on its citizens.

Both of these artistic works present their themes effectively, and both have undoubedtly have had lasting effects on their respective audiences. But the question is inevitable raised: Which one does it better? Naturally when the same story is adapted into another medium, fans of original work want to know whether the original message of the story is retained.