A person’s fear of a king is linked to his recognition of the king’s exalted state and the emotion that accompanies this.
There is also a simpler sense of fear, when a person refrains from doing certain activities due to his social values, because doing them would make him uncomfortable, since he is wary of the opinions of others.
Although this type of fear, a fear of “what will people say,” is not like the sense of trepidation and exalted fear, it is still considered fear.
The same applies to the fear of Heaven.
Take, for example, a person who is afraid and does not steal because there are people around him.
It is not because they are policemen, but just because he does not want to be seen stealing.
If such a person fears Heaven, he will refrain from stealing for the very same reason even when there are no other people around.
His fear of Heaven is on a low level because it does not involve recognition of the divine essence.
But it is nonetheless fear, because the person refrains from acting against God’s will as a result of it.
And for its sake he acts for the sake of God, just as though he possessed the higher level of fear.
Such a person seems to be lacking a spiritual connection with God; he does not understand or feel the fear of God.
Yet he acts in a particular way that correlates to the fear of God, and his way of life is itself an expression of connection.
Rabbi Adin Steinsaltz