Intellectual understanding says “yes,” it agrees. Experiential understanding feels, is obvious. Existential realization is irrefutable. It becomes your very nature.
When one gets an experience, one wants to understand more about it and becomes a seeker. If you have only intellectual understanding, you will think you know it all. Most theologians are in this category. Existential realization contains within it both experiential and intellectual understanding. But it is beyond both of these.