Krishnamurti often said that the word is not the thing, the description is not the described. He often said that what he describes is what is there to be observed, and that he is merely using words to point this out.
Krishnamurti also said that the intellect is partial, and so can only discover things partially. Whereas observation has the potential for insight, which is not partial.
So the intellect has its place, in analysing, describing, using logic, etc, but observation is primary, according to Krishnamurti.
Introspection on the other hand - in the way that Krishnamurti used the word - has to do with self-improvement, a form of observation in which the motive is to transform the observed, rather than merely to observe without choice, without motive. This is why Krishnamurti made a distinction between awareness (or observation) and introspection.
Sources:
You are using intellect as an instrument of analysis… The intellect is partial, is a fragment of the total. You hope to find the cause… through a fragmentary thing called the intellect… So when you begin to enquire into the cause through the intellect, your answer will be partial, because your intellect is partial, and therefore, that is not the instrument…
Up to now we have used the intellect… and the intellect is a fragment of the total. Man is not just his intellect. There is all his nervous organism, the emotions - the whole structure - and you take one part of it and try to use that one part to find the cause. When you examine through a partial instrument, your understanding will always be partial and therefore incomplete.
The intellect is satisfied with theories and explanations, but intelligence is not.
Has the intellect the capacity to examine or does it examine only partially? I see the truth of that, not as a conclusion, not as an opinion, but the fact that the intellect being partial can examine only partially and therefore I no longer use the intellect.
Introspection begins when there is the desire to change the self. I introspect myself in order to transform, modify, change myself into something. That is why we look into ourselves. I am unhappy and I look into myself to find the cause of unhappiness. To introspect is to look into oneself, to change oneself, to modify oneself according to environmental and religious demands. What happens in that process? In that process there is condemnation. I do not like this and I must become that. I am greedy and I must change to be non-greedy. I am angry and I must become peaceful. By that strife you begin to modify. But the effort becomes tyrannic, does it not? This introspection leads nowhere. Have you tried to become introspective? Is there not a continuity in introspection and therefore a bondage? Every experience is translated according to the pattern of the self, which is always examining, translating, interpreting, putting away things which it does not like and accepting things which it wants. So, introspection is a constant struggle to change what is, whereas awareness is the recognition of what is and therefore the understanding of what is. You cannot recognize or understand something when you condemn it. You can understand only when you are observant, when you are not dissecting or pulling apart to see what is.