St John of Chrysostom made a great homily about this which can read here:
http://www.newadvent.org/fathers/170209.htm
To sum, he distinguishes between the servile fear of the Lord that passes away with love,
St John of Chrysostom then gives a second analogy to distinguish the two further: he gives the example of two being tempted into adultery. The one who has a
servile fear of the spouse actually would love to get into the excitement and thrills of adultery, but is just afraid of being found out and outed by the spouse.
The other tempted who has a
filial fear of the spouse dearly loves the spouse, so much so that if the spouse left it would ruin the tempted’s heart and even life because of the hurt, and thus fears the spouse leaving.
And how are these two fears distinguished? …
I would just say,
Re: love God without fearing Him (the topic)
AND
The hierarchy of love.
Jesus answered HERE
Then
Since God is always to be first in the equation… Therefore, … His judgement and His consequences, come 1st over everything, in all we decide.