Is there a difference in having a head knowledge verses a heart knowledge of God?
I believe there is. An example of it could possibly be the stories of king Saul with a head knowledge going through with the priestly duties that he was obviously not anointed for and the story of King David as he dance before the ark, something that seems to have never been heard of before.
We live in a day where lots of folks have a head knowledge of who God is, right or wrong, believer and/or unbelievers, saved and/or unsaved alike. But then there's those folks who regardless of their background in life or denomination who truly seem to know Him not just a book sense but actually know Him. Relationship!
Does relationship come from the head or the heart? Or does it just start in the head and progress to the heart as we grow in relationship with Him? Or at least is surposed to and some get hung up in religion, trusting in man instead of God. Never moving beyond the cross.
I've always heard that the difference is the 10 inches between them. I think the difference is having the acts/power of God displayed in our lives as the fruits of the Spirit. Not that He doesn't move in our lives at all stages of it but that we become increasingly aware of it and began to see the places in our lives that He moves or moves us.