It was said that Kubrick liked the American version because it was hard. The end was Alex returning to a life of crime and evil. Period. The following isn't my opinion, but the publishers: It was thought by Kubrick that an America going through Vietnam wouldn't believe the moral enlightment at the end of the tunnel found in the original. The transformation would be lost to a cynical America, and and ever cynical Kubrick. The man was a walking downer. Burgess hated the omission. It put an entirely different spin on what he was trying to say. But it was also his most successful book, so what was he going to do?
SPOILER: DON'T READ THIS PARAGRAPH IF YOU ARE GOING TO READ THE BOOK.
The book has 3 parts, 6 chapters each part, totaling 18. The last represents the age of maturity, when we are considered adults. It's at that point that Alex, with a new gang, runs into one of his old droogs from the begining of the book. Alex is shocked to meet his mates wife! He's married and is a stand-up citizen. It's after that when Alex has a vision of himself as an old man with grand children bouncing on his knee. He has an urge to create life rather than destroy it. The redemption is that Alex isn't an absolute evil. The point of the book is to illustrate that very point. Judging Alex to be irredeemable is FALSE since he has free will. Chemically conditioning him to alter his (psychotic) brain is FALSE since he hasn't actually changed. Forcing him to be conditioned to be GOOD doesn't change the man.
Their are no moral absolutes. Nothing is pure good or evil. If something was considered to be an absolute it is in fact unnatural....which is the source of the title. An old cockney expression to describe something as being VERY strange or odd was "A clockwork orange." "He's as queer as a clockwork orange he is!" As in a piece of fruit, all the signs of being lush and juicy, but you peel the skin back to expose gears and springs and other mechanical things like that which is found in a clock. That what it appears to be isn't always the truth. There's always more than meets the eye.
Where we find Alex's psychotic behavior repugnant, we feel sympathy for him, we hope he has some good in him...because it's not possible that he's pure evil. Otherwise, if he were, he's be a Clockwork Orange. And eventually, he comes to discover what a waste his youth has been. The killing, rape, the ultra-violence.
It's a really GREAT book about the FREE WILL blessed upon us by god.