Boasting is a grab for praise, covering what we suspect is empty inside. Arrogance, by contrast, is a grasp for power that we don't deserve, that we don't have authority to take. The root cause of arrogance is pride, but between the two stands vanity. We begin with the vertical direction, pride toward God. Pride is an arrogant refusal to let God be God, to grab God's status for oneself, to be one's own boss.
Vanity is the emptiness within that is a result of pride.
The desire to fill tat need of the soul can produce anxiety and arrogance. But love overcomes all of this with humility, the willingness to accept the real relationship between God and one's self. It is the strength to see one's status as a dependent creature - an invaluable, responsible, creative person, yet still a creature who needs the energy of God to exist at all. The humility to accept oneself before God as a sinner with spiritual emptiness is also the grace to plead for and accept forgiveness. The flip side of this self acceptance is that humility is the gift to acknowledge God as Creator, Savior, and Lord.