The occult deals with the keeping and passing down of secret information. These secrets are reserved for the few, the chosen.
The mystical deals with thea experience of the Divine. It is not information, it is the consciousness of God. And it is reserved for the few as well, for those who follow the mystic way.
Gnosticism had both strands in it. Unfortunately, the occult eventually overpowered the mystical and the Church ended up rejecting it. However, they stifled the mystical in the process.
But the mystical survived in the Eastern Orthodox church and was eventually revived in the Roman Catholic Church. The Pentecostal movement was mystical in its origin. But Evangelicals tend to have a relationship with the Bible rather than an actual relationship with God.
As a progressive Christian, I am sympathetic to Christian Gnosticism, but I reject the occult elements. I believe mysticism is the lifeblood of vital Christianity. Once we lose conscious connection with God, Christianity becomes merely a system of morality.