It is something random, uncontrolled. Cloning would select the genetic composition of some existing person and try and make another individual with the same genes. It is an intentional, controlled act to produce a specific known end. The crucial point is not the genetic identity but the human act of control of it. The most fundamental ethical case against human cloning is that no human being should have their complete genetic make up pre-determined by another human.
Cloning is also instrumental.
Parents influence and select for their children in a thousand ways socially, but so far they have never been able to choose their genes for them. We can reject their upbringing, but we cannot change our genes. In most of the cases people have speculated about, like providing a donor for bone marrow for a sibling with leukaemia, the person cloned would not be created for their own benefit but someone else's. This is an instrumental way of using another human, as a means to someone else's ends. An exception might be cloning one member of a couple to solve infertility, but this would raise other profound problems.