When you're awake there is a completely different feeling of awareness. When we do reality checks in real life we know were not dreaming but we have to seriously consider that we might be to make it effective. I believe "lucidity" is being aware that we are in a dreaming state and not awake. However the amount of consciousness can vary greatly.

Coming from someone who has close to no experience in lucid dreaming and only had my first "Lucid" dream last night.