It seems to me, that the confusion regarding the word missile, comes from it having two uses/meanings. As this link shows http://dictionary.cambridge.org/dictionary/british/missile?q=missile , it has a particular, military meaning and, a general meaning.
It can be a particular kind of military weapon, but it can be any object that is thrown with the intention of causing injury or damage.
In the context of the question, which is the Malaysian airliner that crashed in Ukraine, the particular, military meaning applies. The introduction of the article at the following link http://en.wikipedia.org/wiki/Missile , states "In a modern military usage, a missile, or guided missile, is a self-propelled guided weapon system, as opposed to an unguided self-propelled munition, referred to as just a rocket."
In other words, in a military context, a rocket is an unguided, rocket-powered weapon, with no steering ability. A missile is a self-propelled weapon, often rocket-powered (but not always), that has some kind of guidance system so that it can steer in flight, towards its target.
That would be why someone pointed out on BBC News that the Malaysian plane was hit not by a 'rocket' but by a 'missile'. It is very unlikely that an unguided rocket fired from land, which requires a direct hit on its target, to explode, would be able to hit an aircraft in flight, especially one flying as high as that airliner was reported to be. Potential attackers would have to use a missile, which can steer towards its target and would have a proximity fuse http://en.wikipedia.org/wiki/Proximity_fuze , which means that it would not require a direct hit on its target, to explode.